Allows a button type for menus, used in Conpherence

Summary: This adds a new menu item, TYPEBUTTON, for use in Conpherence and maybe others over time. Note I need to add icon support, but I'll make them later tonight. I also changed the front facing names to 'Conversations' which is way more natural. Basically, Pholio has Mocks, Differential has Diffs, Conpherence has Conversations.

Test Plan: Tested Conpherence on mobile and desktop.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2430

Differential Revision: https://secure.phabricator.com/D4691

src/applications/conpherence/controller/ConpherenceNewController.php

@@ -12,7 +12,7 @@ final class ConpherenceNewController extends ConpherenceController {
     $conpherence = id(new ConpherenceThread())
       ->attachParticipants(array())
       ->attachFilePHIDs(array());
-    $title = pht('New Conpherence');
+    $title = pht('New Conversation');
     $participants = array();
     $message = '';
     $files = array();