Bump omniauth-gitlab to 1.0.2 to fix incompatibility with omniauth-oauth2

As noted in gitlab-com/support-forum#1270, omniauth-gitlab fails if omniauth-oauth2 is bumped to 1.4.0, OAuth2 quietly fails due to https://github.com/linchus/omniauth-gitlab/issues/10:

21:26:04 rails-web.1             | I, [2016-11-07T21:26:04.245007 #56637]  INFO -- omniauth: (gitlab) Callback phase initiated.
21:26:05 rails-web.1             | E, [2016-11-07T21:26:05.068009 #56637] ERROR -- omniauth: (gitlab) Authentication failure! invalid_credentials: OAuth2::Error, invalid_grant: The provided authorization grant is invalid, expired, revoked, does not match the redirection URI used in the authorization request, or was issued to another client.

This was fixed and discussed here:

• https://github.com/linchus/omniauth-gitlab/commit/26c47e55396205fab8439363c98136d0fde797f3
• https://github.com/linchus/omniauth-gitlab/issues/10

Bumping this version to 1.0.2 will ensure future compatibility.