modified attribute groups to be an array ref
modified attribute groups to be an array ref

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