Email on push inline diff
Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3087 and https://gitlab.com/gitlab-org/gitlab-ce/issues/12821
I will backport 16745c1bb386443d8ea3395d23048b1d40ea0b56 and 92c2effbb334246bfed15a0fd78a58f1cfc8be34 to CE.
In a regular browser:
In Gmail (in Chrome):
Gmail doesn't like monospace fonts, apparently, but that's acceptable.