Merge branch 'accept_mr_btn_ci_status' into 'master'

Merge button has color from CI status

This MR closes #3313

I'am not realy sure about the color for the skipped status (red)...

UI changes:

![accpet-mr-ci-failed](/uploads/c03970c468b89e38ed2c5e3171f53505/accpet-mr-ci-failed.png)

![accpet-mr-ci-skipped](/uploads/f29cbc69e77cc95b33522135b327cc51/accpet-mr-ci-skipped.png)

![accpet-mr-ci-pending](/uploads/79612a66fd497174e00bd348c9cba69c/accpet-mr-ci-pending.png)

![accpet-mr-ci-success](/uploads/4b601e6d02b860db5ff53c47c98f3206/accpet-mr-ci-success.png)


See merge request !1761

app/assets/stylesheets/pages/merge_requests.scss

@@ -19,6 +19,20 @@
   .accept-merge-holder {
     .accept-action {
       display: inline-block;
+
+      .accept_merge_request {
+        &.ci-pending,
+        &.ci-running {
+          @include btn-orange;
+        }
+
+        &.ci-skipped,
+        &.ci-failed,
+        &.ci-canceled,
+        &.ci-error {
+          @include btn-red;
+        }
+      }
     }
 
     .accept-control {

app/views/projects/merge_requests/widget/open/_accept.html.haml

+- status_class = @merge_request.ci_commit ? " ci-#{@merge_request.ci_commit.status}" : nil
+
 = form_for [:merge, @project.namespace.becomes(Namespace), @project, @merge_request], remote: true, method: :post, html: { class: 'accept-mr-form js-requires-input' } do |f|
   = hidden_field_tag :authenticity_token, form_authenticity_token
   .accept-merge-holder.clearfix.js-toggle-container
     .accept-action
-      = f.button class: "btn btn-create accept_merge_request" do
+      = f.button class: "btn btn-create accept_merge_request#{status_class}" do
         Accept Merge Request
     - if can_remove_branch?(@merge_request.source_project, @merge_request.source_branch) && !@merge_request.for_fork?
       .accept-control.checkbox