Send cherry-picking errors to Sentry

Except in the case of a 400 bad request (generic "cherry-pick failed" message).

1a65f1a3 - Minor auto_deploy:pick task cleanup

It didn't make sense to only show the version number for these, so now we show the project and auto-deploy branch name.

We also exit instead of return, since we're in a Rake task.

f0317090 - Remove extra newline in CI config