Merge branch 'create_issue_header' into 'master'

New Issue Header

Fixes #2073

- I've switched it from "New Issue" to "Create Issue". Small change, but grammatically correct.

See merge request !1611

app/views/projects/issues/_form.html.haml

 %div.issue-form-holder
-  %h3.page-title= @issue.new_record? ? "New Issue" : "Edit Issue ##{@issue.iid}"
+  %h3.page-title= @issue.new_record? ? "Create Issue" : "Edit Issue ##{@issue.iid}"
   %hr
 
   = form_for [@project.namespace.becomes(Namespace), @project, @issue], html: { class: 'form-horizontal issue-form gfm-form' } do |f|