added test to make sure gene display_xref_id was being set by store method
added test to make sure gene display_xref_id was being set by store method

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