Merge branch 'sh-fix-ruby-2-1' into 'master'

Fix Hash syntax to work for both Ruby 2.1 and 2.3

Ruby 2.1 specs were failing (e.g. https://gitlab.com/gitlab-org/gitlab-ce/builds/5149275) due the error:

```
SyntaxError: /builds/gitlab-org/gitlab-ce/app/views/devise/shared/_tabs_normal.html.haml:3: syntax error, unexpected ':', expecting =>
...'#login-pane', data: {'toggle':'tab'}, role: 'tab')).to_s));...
```

See merge request !6917

app/views/devise/shared/_tabs_normal.html.haml

 %ul.nav-links.new-session-tabs.nav-tabs{ role: 'tablist'}
   %li.active{ role: 'presentation' }
-    %a{ href: '#login-pane', data: {'toggle':'tab'}, role: 'tab'} Sign in
+    %a{ href: '#login-pane', data: { toggle: 'tab' }, role: 'tab'} Sign in
   %li{ role: 'presentation'}
-    %a{ href: '#register-pane', data: {'toggle':'tab'}, role: 'tab'} Register
+    %a{ href: '#register-pane', data: { toggle: 'tab' }, role: 'tab'} Register