Cleanup: prevent null pointer exception

Prevent null pointer exception when no dao.getFieldMapLabels found on
particular proj. Id
Added separate constants for use in OntologyDataManager

- Added separate constants for use in OntologyDataManager
- Added constants for Terms
Applied constants in testFindTermByName(...)
Added not empty assertion on testFindTermByNameOrSynonym

- Added not empty assertion on testFindTermByNameOrSynonym
- Added new constants