Consequence type gbpa

- Added RefseqAccession and Hgvs classes
- Added spock tests for RefseqAccesion and Hgvs and test resource 'testReferenceSequence.fasta' and fai
- Added dependencies to maven: spock, and gmaven plugin (used to compile groovy)
- Added 'transformToEnsemblFormat' method to Variant and junit test for this method