UX improvements based on user testing

Unclear how to enable CI for the project #14483 (moved)
When edit file placeholder in commit message is useless because I need to type it anyway
When edit file its unclear that you can create new branch or merge request https://gitlab.com/gitlab-org/gitlab-ce/issues/17385
When import projects from github/bitbucket there is no feedback on pressing import button - https://gitlab.com/gitlab-org/gitlab-ce/commit/a2e9ca12d8075382442bc1b46ae0d066d0653c00
Left sidebar is confusing (changing context, people don't understand that it has hierarchy...). #14838 (closed)
Too many items in left sidebar #14907 (closed)