Prepare Diffusion for hovercards

Summary:
Move Diffusion to be hovercard-ready, and expand our ability to resolve commit references.

  - Link unqualified hashes of 7 characters or more which match a commit.
  - Link qualified hashes of 5 characters or more which match a commit.
  - Support `{...}` syntax.

Test Plan: {F33896}

Reviewers: chad, vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D5121

src/applications/diffusion/application/PhabricatorApplicationDiffusion.php

@@ -30,6 +30,12 @@ final class PhabricatorApplicationDiffusion extends PhabricatorApplication {
     );
   }
 
+  public function getRemarkupRules() {
+    return array(
+      new DiffusionRemarkupRule(),
+    );
+  }
+
   public function getRoutes() {
     return array(
       '/r(?P<callsign>[A-Z]+)(?P<commit>[a-z0-9]+)'