This change adds more unit tests to the rolling OSD upgrade
scenario to ensure more complete coverage.
Change-Id: Ibd7c8d6c46520957a3298446efc6b5fff210a51a
Related-Bug: #1662591
Helper functions for the ceph charms. This library has shared functionality that is used in the ceph-mon, ceph-osd and ceph
charms. Anything that needs to be shared across the ceph charms should live here.