Improve responsive UI for tablets and mobile views
Do it only after we done with stable UI for desktop version.
Should be same as desktop view but with 60% of controls/information hidden so it fit small screens.
cc @creamzy @jschatz1 @skyruler
TODO:
-
Hide left sidebar on phone screen because horizontal space is quite limited - https://gitlab.com/gitlab-org/gitlab-ce/issues/17323