Fix conflict in app/assets/javascripts/vue_merge_request_widget/components/states/nothing_to_merge.vue

Fix encoding of branch names on compare and new merge request page

Closes #46627

See merge request gitlab-org/gitlab-ce!19143

Upgrade to Bootstrap 4

Closes #45185 and #46710

See merge request gitlab-org/gitlab-ce!18232

Upgrade to Bootstrap 4 (EE)

Closes #5767

See merge request gitlab-org/gitlab-ee!5474

CE upstream - 2018-05-25 18:23 UTC

See merge request gitlab-org/gitlab-ee!5857

Merge branch '46740-projectmilestones-setting-start_date-via-the-api-requires-a-second-parameter' into 'master'

Resolve "ProjectMilestones: Setting start_date via the API requires a second parameter"

Closes #46740

See merge request gitlab-org/gitlab-ce!19133