Merge branch 'leave-project-btn' into 'master'

Move buttons to project header

Closes #25692    
Before:   
<img src="/uploads/fb65f1ca8021f1669071a3980e5f8258/Screen_Shot_2016-12-14_at_3.52.19_PM.png" width="800px">
After (with Koding setup):   
<img src="/uploads/236e0103186a1b482c4302aa3a4b94b1/Screen_Shot_2016-12-16_at_10.09.53_AM.png" width="800px">
After (without Koding setup):
<img src="/uploads/04bc8360831c98a4c86d3b11ee24826d/Screen_Shot_2016-12-16_at_10.18.35_AM.png" width="800px">


See merge request !8095