Make the Aphlict server more resilient.

Summary:
Currently, the Aphlict server will crash if invalid JSON data is `POST`ed to it. I have fixed this to, instead, return a 400. Also made some minor formatting changes.

Ref T4324. Ref T5284. Also, modify the data structure that is passed around (i.e. `POST`ed to the Aphlict server and broadcast to the Aphlict clients) to include the subscribers. Initially, I figured that we shouldn't expose this information to the clients... however, it is necessary for T4324 that the `AphlictMaster` is able to route a notification to the appropriate clients.

Test Plan:
Making the following `curl` request: `curl --data "{" http://localhost:22281/`.

**Before**
```
sudo ./bin/aphlict debug
Starting Aphlict server in foreground...
Launching server:

    $ 'nodejs' '/usr/src/phabricator/src/applications/aphlict/management/../../../../support/aphlict/server/aphlict_server.js' --port='22280' --admin='22281' --host='localhost' --user='aphlict'

[Wed Jun 11 2014 17:07:51 GMT+0000 (UTC)] Started Server (PID 2033)
[Wed Jun 11 2014 17:07:55 GMT+0000 (UTC)]
<<< UNCAUGHT EXCEPTION! >>>

SyntaxError: Unexpected end of input
>>> Server exited!
```

**After**
(No output... the bad JSON is caught and a 400 is returned)

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T4324, T5284

Differential Revision: https://secure.phabricator.com/D9480

support/aphlict/server/aphlict_server.js

@@ -25,10 +25,10 @@ if (config.logfile) {
 
 function parse_command_line_arguments(argv) {
   var config = {
-    port : 22280,
-    admin : 22281,
-    host : '127.0.0.1',
-    user : null,
+    port: 22280,
+    admin: 22281,
+    host: '127.0.0.1',
+    user: null,
     log: '/var/log/aphlict.log'
   };
 
@@ -36,10 +36,10 @@ function parse_command_line_arguments(argv) {
     var arg = argv[ii];
     var matches = arg.match(/^--([^=]+)=(.*)$/);
     if (!matches) {
-      throw new Error("Unknown argument '"+arg+"'!");
+      throw new Error("Unknown argument '" + arg + "'!");
     }
     if (!(matches[1] in config)) {
-      throw new Error("Unknown argument '"+matches[1]+"'!");
+      throw new Error("Unknown argument '" + matches[1] + "'!");
     }
     config[matches[1]] = matches[2];
   }
@@ -52,19 +52,19 @@ function parse_command_line_arguments(argv) {
 
 if (process.getuid() !== 0) {
   console.log(
-    "ERROR: "+
-    "This server must be run as root because it needs to bind to privileged "+
-    "port 843 to start a Flash policy server. It will downgrade to run as a "+
-    "less-privileged user after binding if you pass a user in the command "+
+    "ERROR: " +
+    "This server must be run as root because it needs to bind to privileged " +
+    "port 843 to start a Flash policy server. It will downgrade to run as a " +
+    "less-privileged user after binding if you pass a user in the command " +
     "line arguments with '--user=alincoln'.");
   process.exit(1);
 }
 
 var net = require('net');
-var http  = require('http');
+var http = require('http');
 var url = require('url');
 
-process.on('uncaughtException', function (err) {
+process.on('uncaughtException', function(err) {
   debug.log("\n<<< UNCAUGHT EXCEPTION! >>>\n\n" + err);
   process.exit(1);
 });
@@ -95,7 +95,7 @@ var send_server = net.createServer(function(socket) {
     debug.log('<%s> Ended Connection', listener.getDescription());
   });
 
-  socket.on('error', function (e) {
+  socket.on('error', function(e) {
     debug.log('<%s> Error: %s', listener.getDescription(), e);
   });
 
@@ -107,23 +107,29 @@ var messages_in = 0;
 var start_time = new Date().getTime();
 
 var receive_server = http.createServer(function(request, response) {
-  response.writeHead(200, {'Content-Type' : 'text/plain'});
-
   // Publishing a notification.
   if (request.method == 'POST') {
     var body = '';
 
-    request.on('data', function (data) {
+    request.on('data', function(data) {
       body += data;
     });
 
-    request.on('end', function () {
-      ++messages_in;
+    request.on('end', function() {
+      try {
+        var msg = JSON.parse(body);
 
-      var msg = JSON.parse(body);
-      debug.log('notification: ' + JSON.stringify(msg));
-      broadcast(msg.data);
-      response.end();
+        debug.log('notification: ' + JSON.stringify(msg));
+        ++messages_in;
+        broadcast(msg);
+
+        response.writeHead(200, {'Content-Type': 'text/plain'});
+      } catch (err) {
+        response.statusCode = 400;
+        response.write('400 Bad Request');
+      } finally {
+        response.end();
+      }
     });
   } else if (request.url == '/status/') {
     request.on('data', function(data) {
@@ -139,9 +145,10 @@ var receive_server = http.createServer(function(request, response) {
         'messages.in': messages_in,
         'messages.out': messages_out,
         'log': config.log,
-        'version': 5
+        'version': 6
       };
 
+      response.writeHead(200, {'Content-Type': 'text/plain'});
       response.write(JSON.stringify(status));
       response.end();
     });