added option to specify release number
added option to specify release number

james-monkeyshines/ensembl,danstaines/ensembl,Ensembl/ensembl,at7/ensembl,Ensembl/ensembl,mjg17/ensembl,muffato/ensembl,james-monkeyshines/ensembl,willmclaren/ensembl,mjg17/ensembl,james-monkeyshines/ensembl,at7/ensembl,willmclaren/ensembl,mjg17/ensembl,at7/ensembl,at7/ensembl,muffato/ensembl,muffato/ensembl,danstaines/ensembl,mjg17/ensembl,danstaines/ensembl,muffato/ensembl,james-monkeyshines/ensembl,Ensembl/ensembl,Ensembl/ensembl