Remove EE-only inline coffeescript filters

We need to stop using inline :coffeescript filters in our views. See https://git.io/vztMu and http://stackoverflow.com/a/17571242/223897

• app/views/projects/_merge_request_settings.html.haml - @vsizov / @dzaporozhets
• app/views/shared/issuable/_form.html.haml - @vsizov
• app/views/projects/merge_requests/widget/open/_ff_accept.html.haml - @vsizov

This will let us reintroduce https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2380