patch also tracked at http://tracker.deltacloud.org/set/345
This moves the 'valid_credentials?' method to base_driver where possible. For some drivers - namely ec2, gogrid, google and fgcp - the 'valid_credentials' check deviates in that it isn't enought to just get a handle to the provider to determine if the credentials are valid (e.g. you have to make a request for some resource and catch the 401 response). marios
