Added fetch in inityialize and exception throwing in internal-id
Added fetch in inityialize and exception throwing in internal-id

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