Add ceph partitioning scheme support for fuel_agent

* Add ability to set GUID for partitions;
* Bare unit tests;
* Backport ceph code from pmanager.py

Partially implements: blueprint image-based-provisioning
Change-Id: Id23033a537b150875e452f81bd52d63f6286fa1d
Merge "Add ceph partitioning scheme support for fuel_agent"