RootReport through Taskmanager

Reason:
- guestagent should be free from direct Trove back-end DB connection.
Changes:
- extending taskmanager provisioning flow;
- taskmanager reports about root creation;
- tests.

Closes-bug: #1257489
Change-Id: I5f2502d8b61542658682a5ff74735749e5a1ca2b
Merge "RootReport through Taskmanager"