added get_unit and test
Merge branch 'validate_unit' of https://github.com/mbarry02/coi-services into validate_unit

Conflicts:
	ion/processes/bootstrap/ion_loader.py
	ion/services/dm/utility/test/test_types.py
	ion/services/dm/utility/types.py
Warning message fix
Merge pull request #891 from lukecampbell/validate_unit

Adds unit validation pending udunitspy