Refactor periodic "tips" jobs
Refactor periodic "tips" jobs

Two changes:
1 - declare the abstract base tips jobs 'abstract'
2 - add a branch matcher to where the periodic tips jobs
    are invoked in the project definition so that they only
    apply to the master branch

Change-Id: If80ead2796c370b9539a0d7dd12bb8d35de8abcf

openstack/python-glanceclient,openstack/python-glanceclient