Cache connection in bin/storage

Summary: Connection takes .3s from dev server to master.

Test Plan:
  $ bin/storage --trace upgrade --namespace x
  $ bin/storage --trace destroy --namespace x

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4480

scripts/sql/manage_storage.php

@@ -85,7 +85,7 @@ $api->setNamespace($args->getArg('namespace'));
 
 try {
   queryfx(
-    $api->getConn('meta_data', $select_database = false),
+    $api->getConn(null),
     'SELECT 1');
 } catch (AphrontQueryException $ex) {
   echo phutil_console_format(