tests: add the ability to run tests with shaman repos
tests: add the ability to run tests with shaman repos

To run tests that deploy shaman repos set CEPH_DEV=true and optionally
use CEPH_DEV_BRANCH and CEPH_DEV_SHA1 to define with branch and sha1 to
test. CEPH_DEV_BRANCH defaults to master and CEPH_DEV_SHA1 defaults to
latest.

For example, this would run the journal_collocation test with the latest
build of the master branch:

  CEPH_DEV=true tox -rve ansible2.2-journal_collocation

Signed-off-by: Andrew Schoen <1bb641dc23c3a93cce4eee683bcf4b2bea7903a3@redhat.com>

travmi/ceph-ansible,albertomurillo/ceph-ansible,jtaleric/ceph-ansible,fgal/ceph-ansible,ceph/ceph-ansible,travmi/ceph-ansible,fgal/ceph-ansible,WingkaiHo/ceph-ansible,font/ceph-ansible,jtaleric/ceph-ansible,ceph/ceph-ansible,albertomurillo/ceph-ansible,bengland2/ceph-ansible,WingkaiHo/ceph-ansible,albertomurillo/ceph-ansible,bengland2/ceph-ansible,font/ceph-ansible,WingkaiHo/ceph-ansible