Add a meta-application

Summary:
  - Adds a new "Applications" application.
  - Builds an application list via application config instead of via hard-coding, so we can move toward better concepts of installing/uninstalling applications, etc.
  - Applications indicate that they need attention with notice counts and brief status messages rathern than 50 giant tables of all sorts of app data.

I want to try replacing the home screen with this screen, pretty much. Not sure if this is totally crazy or not. What does everyone else think?

Test Plan: Will add screenshots.

Reviewers: btrahan, chad, vrana, alanh

Reviewed By: vrana

CC: aran, davidreuss, champo

Maniphest Tasks: T1569

Differential Revision: https://secure.phabricator.com/D3129

src/applications/base/PhabricatorApplication.php

@@ -57,6 +57,10 @@ abstract class PhabricatorApplication {
     return PhabricatorUser::getDefaultProfileImageURI();
   }
 
+  public function shouldAppearInLaunchView() {
+    return true;
+  }
+
 
 /* -(  URI Routing  )-------------------------------------------------------- */
 
@@ -74,6 +78,14 @@ abstract class PhabricatorApplication {
   }
 
 
+/* -(  Launch Integration  )------------------------------------------------- */
+
+
+  public function loadStatus(PhabricatorUser $user) {
+    return array();
+  }
+
+
 /* -(  Application Management  )--------------------------------------------- */