Ruby metrics plugin support added

Rcov plugin parses rcov html report files and
shows it in Jenkins with a trend graph.

Change-Id: I1f1d177c8681e68e5c12b520e263648842c701d0
Merge "Ruby metrics plugin support added"
Migrate to pbr

I found out pbr to be a bit nicer when it comes to edit files. AFAIK
most OpenStack project are using it, so I guess Jenkins Job Builder can
be pbr based as well.o

Basically:
* moved everything from setup.py to setup.cfg
* sorted entries while at it
* require pbr module using the same version limits used by Zuul
* enable pbr.warnerrors
* testenv.usedevelop = True or build_sphinx can not find entry points
* move requirement files to root of repository (we had them in /tools/)

Change-Id: I44ee8910ad4fe4eebb7337951efa31baff4281fe
Install the jenkins_jobs package on setup

Since the conversion to PBR it looks like there is an omission of
the [files] section in the setup.cfg. This means that the metadata
was installed for the jenkins-job-builder but the package with the
python code was not. This patchset adds the [files] section in to
correct this oversight.

Closes-Bug: 1292745
Change-Id: Ia1b8f022a66574ee371587d49bb46c43d80f01ba