made all registry calls case INsensetive as it was very annoying having to...

made all registry calls case INsensetive as it was very annoying having to have species, group and type all in the correct case. Also added load_registry_from_db which will load the latest ensembl databases given a database host (and optionally port, user, pass) to search. At prsent only core,variation,estgene,compara and go adaptors are loaded via this method.