Add support for redmine [$15]

[vollmerk]

the ruby trac http://www.redmine.org/

There is a $15 open bounty on this issue. Add to the bounty at Bountysource.

[rappo]

Example project using Redmine:
https://www.bountysource.com/#issues/116703-add-ability-to-restrict-ldap-authentication-to-a-security-group
http://projects.theforeman.org/issues/863
https://labs.parabola.nu/issues