Rollback screen improvements

[matthieu-beteille]

Love the feature, here are some things I wish I could do from the rollback screen:

• Being able to see the commit of each image (similar to what we see in the deployments page), right now the SHA is not that helpful
• Remove older images manually in a simple click

[ksaitor]

• Move Rollback functionality from Configuration to Deployments tab
• In Configuration -> Rollback, users should be able to config number of containers to keep at any time, for instant rollback

Rollback button example: