Change double quotes to single quotes.

Summary: Ran `arc lint --apply-patches --everything` over rP, mainly to change double quotes to single quotes where appropriate. These changes also validate that the `ArcanistXHPASTLinter::LINT_DOUBLE_QUOTE` rule is working as expected.

Test Plan: Eyeballed it.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin, hach-que

Differential Revision: https://secure.phabricator.com/D9431

src/applications/diffusion/controller/DiffusionController.php

@@ -11,7 +11,7 @@ abstract class DiffusionController extends PhabricatorController {
 
   protected function getDiffusionRequest() {
     if (!$this->diffusionRequest) {
-      throw new Exception("No Diffusion request object!");
+      throw new Exception('No Diffusion request object!');
     }
     return $this->diffusionRequest;
   }
@@ -104,7 +104,7 @@ abstract class DiffusionController extends PhabricatorController {
       $crumb = new PhabricatorCrumbView();
       if ($spec['commit']) {
         $crumb->setName(
-          pht("Tags for %s", 'r'.$callsign.$stable_commit));
+          pht('Tags for %s', 'r'.$callsign.$stable_commit));
         $crumb->setHref($drequest->generateURI(
           array(
             'action' => 'commit',