Allows user to define its own gitpathmapping for CMDB git changes

http://ralph-ci.office/buildbot/builders/unittest-ralph-vi4m/builds/125
http://ralph.allegrogroup.com/buildbot//builders/unittest-ralph-vi4m/builds/125


Allows user to define gitpathmapping in the django admin, with  the form of:

{file path} -> {choosenCI}

Changesets paths from git are now processed as described:

Try to detect path in following order:
1. modules/ventures/([^\/]+)/files/(.*)')
2. modules/ventures/([^\/]+)/manifests/(.*)
3. else if any gitpathmapping matched, return its CI and stop further processing