Reorganize mappingservice.implementation

Reorganize mappingservice.implementation

This consists of a number of incremental changes ultimately meant to
ensure the clear separation between the components implementing the LISP
control plane logic (MapServer/MapResolver) and the logic used to
manipulate the database that stores mapping state. This should give us
better isolation (i.e, should help testing) but also opens the
possibility to better optimize DAO/map-cache implementation for specific
use-cases, if needed.

Noteworthy changes:
- Move out code concerning logic behind CRUD operations on DAO from
  MapServer and MapResolver to DAOMappingUtil. In future patches the
  latter will be converted to a MapCache class instead of a helper
  class.
- Move serializer and LISP protocol utility functions from
  mappingservice.implementation to yangmodel.
- Remove bundle dependencies on mappingservice.implementation. Bundles
  should be importing mappingservice.api.
- Cleanup pom files

Change-Id: I199b8d2162cd2ab2b54cd3340eb24811fd6cd5be
Signed-off-by: Florin Coras <fcoras@cisco.com>