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));...

Enabled an automatic merge when the build for fa25f61d succeeds

Reassigned to @stanhu

Canceled the automatic merge

Status changed to merged

Mentioned in commit a7e9490d