added regression test: misc feature without attributes can be stored
added regression test: misc feature without attributes can be stored

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