When issuing a 'Rebase' the committer will now be the logged in user

When doing a Rebase from UI, the committer will now be the user
that pressed the button. The preferred email address will be chosen
if the user has several registered with Gerrit. Previously Gerrit
was set as a committer, which caused confusion for our users.

Change-Id: I32c96c2f1c63eb9e3666cf5a6f46892b765f0686
4 files changed