Merge branch '500-message' into 'master'

500 Message

public/500.html

@@ -8,6 +8,6 @@
   <h1>500</h1>
   <h3>We're sorry, but something went wrong.</h3>
   <hr/>
-  <p>We've been notified about this issue and we'll take a look at it shortly.</p>
+  <p>Please contact your GitLab administrator if this problem persists.</p>
 </body>
 </html>

public/502.html

@@ -8,6 +8,6 @@
   <h1>502</h1>
   <h3>GitLab is not responding.</h3>
   <hr/>
-  <p>Please contact your administrator if this problem persists.</p>
+  <p>Please contact your GitLab administrator if this problem persists.</p>
 </body>
 </html>