BUG: MRS task data provider definition is incorrect

 The data provider defines lookup types for Patient, Facility etc.
 But the domain objects have been renamed to MRSPatient, MRSFacility etc.
 So the data provider definition has been changed appropriately.

 https://trello.com/c/N48o7n7l/

Change-Id: I10eb87877e8d1f7810675cba5b29cdd47ff64c83