Merge branch '14762-delete-button' into 'master'

Update delete button

Closes #14762 

![Screen_Shot_2016-04-11_at_5.21.32_PM](/uploads/fef09645eb70fc0fcaee359245664ddc/Screen_Shot_2016-04-11_at_5.21.32_PM.png)

See merge request !3665

app/views/shared/issuable/_form.html.haml

@@ -128,8 +128,6 @@
   - else
     .pull-right
       - if current_user.can?(:"destroy_#{issuable.to_ability_name}", @project)
-        = link_to polymorphic_path([@project.namespace.becomes(Namespace), @project, issuable]), data: { confirm: "#{issuable.class.name.titleize} will be removed! Are you sure?" },
-                                                                                                  method: :delete, class: 'btn btn-grouped' do
-          = icon('trash-o')
-          Delete
+        = link_to 'Delete', polymorphic_path([@project.namespace.becomes(Namespace), @project, issuable]), data: { confirm: "#{issuable.class.name.titleize} will be removed! Are you sure?" },
+                                                                                                  method: :delete, class: 'btn btn-danger btn-grouped'
       = link_to 'Cancel', polymorphic_path([@project.namespace.becomes(Namespace), @project, issuable]), class: 'btn btn-grouped btn-cancel'