Security issue: imported URLs are stored along with password.

1. Mask the password in logs.
2. Remove origin in newly imported repo.

Last issue remains - the password is passed to git on the command-line, but I'm not sure how to fix that. Also, it's not as critical.
WAT? The other bot on gitlabhq repo told me directly the opposite. [Here](https://github.com/gitlabhq/gitlabhq/pull/7601#discussion_r16780609).