Add ability to use email in Gitlab authentication

Review Request #5591 — Created March 8, 2014 and submitted — Latest diff uploaded

Information

Review Board
release-1.7.x
3fb29b2...

Reviewers

Older versions of Gitlab API v3 only allow authentication using email instead of "login" parameter that Review board currently uses.

See https://github.com/gitlabhq/gitlabhq/commit/559e83d30004e0c41a30f4ce3463f695eb7e26a1

Unit tests pass. Tested authentication with email againts different versions of Gitlab.