Improve Facility Manager + Client Manager

This change improves the tests and documentation of the facility manager.
Attempting to retrieve a facility with an unknown facility id now calls failure.
Client manager has been modified to populate the error object of failure callbacks.

PPRFacilityManger
- improve documentation and call failure on unknown facilityId

PPRFacilityManagerTests
- add getFacilityById test

PPRClientManager
-
Merge pull request #21 from davidbernard/facility_manager

Facility manager