Added new MagnetoDB project to Stackforge

MagnetoDB is key-value database service for OpenStack cloud.
More details https://wiki.openstack.org/wiki/MagnetoDB

Change details:

* gerritbot configuration
* Stackforge acls for project configured
* job builder config updated
* zuul layout extended with new project

Change-Id: Ieebdc56441714020e23e889140f5612253863aa1
Merge "Added new MagnetoDB project to Stackforge"