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

scripts/ssh/ssh-auth.php

@@ -16,7 +16,7 @@ $rows = queryfx_all(
   $ssh_dao->getTableName());
 
 if (!$rows) {
-  echo pht("No keys found.")."\n";
+  echo pht('No keys found.')."\n";
   exit(1);
 }