added new classes: CellBaseLoadMain, ClinicalMongoDBLoader, MongoDBLoader, CellbaseMongoDBSerializer
Finished Clinical MongoDB Loader
added Clinical MongoDB Loader test, and dependencies for spock tests
ClinicalVariation: small changes to avoid serialize chrom, start, end, ref and alt more than once for the same object
removed unused imports
Moved ClinicalVariation to cellbase-mongodb
Merged feature/clinicalMongoDBLoader branch into consequence-type-gbpa