Use launchpad prop to store link to the lp project

It was already implemented in jeepyb.
https://github.com/openstack-infra/jeepyb/blob/master/jeepyb/projects.py
Most of the mappings was taken from this file.

Change-Id: I50b05b0a5f96f53e8d97d691b3c25c4a493f2c1e
Merge "Use launchpad prop to store link to the lp project"