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/fact/controller/PhabricatorFactChartController.php

@@ -32,7 +32,7 @@ final class PhabricatorFactChartController extends PhabricatorFactController {
 
     if (!$points) {
       // NOTE: Raphael crashes Safari if you hand it series with no points.
-      throw new Exception("No data to show!");
+      throw new Exception('No data to show!');
     }
 
     // Limit amount of data passed to browser.