Merge branch '23557-remove-extra-line-for-empty-issue-description' into 'master'

removes extra line for empty description

## What does this MR do?
This MR removes an odd line for empty description 
## Are there points in the code the reviewer needs to double check?
Not necessary
## Why was this MR needed?
Improve UX 
## Screenshots (if relevant)
**Before**
![ss__2016-10-19_at_11.04.45_PM](/uploads/12b376c772115c2e5eef2fe0c0d1992f/ss__2016-10-19_at_11.04.45_PM.png)
**After**
![edi](/uploads/89fea59ef5267974af4cbe1064dc521a/edi.png)
## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG.md) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #23557 #23695

See merge request !7045

CHANGELOG.md

@@ -15,7 +15,7 @@ Please view this file on the master branch, on stable branches it's out of date.
   - Fix error in generating labels
 
 ## 8.13.0 (2016-10-22)
-
+  - Removes extra line for empty issue description. (!7045)
   - Fix save button on project pipeline settings page. (!6955)
   - All Sidekiq workers now use their own queue
   - Avoid race condition when asynchronously removing expired artifacts. (!6881)

app/assets/stylesheets/framework/common.scss

@@ -372,3 +372,5 @@ table {
   margin-right: -$gl-padding;
   border-top: 1px solid $border-color;
 }
+
+.hide-bottom-border { border-bottom: none !important; }

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

@@ -53,7 +53,7 @@
 
 
 .issue-details.issuable-details
-  .detail-page-description.content-block
+  .detail-page-description.content-block{ class: ('hide-bottom-border' unless @issue.description.present? ) }
     %h2.title
       = markdown_field(@issue, :title)
     - if @issue.description.present?

app/views/projects/milestones/show.html.haml

@@ -31,7 +31,7 @@
         = link_to namespace_project_milestone_path(@project.namespace, @project, @milestone), data: { confirm: 'Are you sure?' }, method: :delete, class: "btn btn-grouped btn-danger" do
           Delete
 
-  .detail-page-description.milestone-detail
+  .detail-page-description.milestone-detail{ class: ('hide-bottom-border' unless @milestone.description.present? ) }
     %h2.title
       = markdown_field(@milestone, :title)
     %div