adwords-api 0.8.1 released

AdWords 0.8.1 is out. This is a maintenance release from version 0.8. In this release we changed the default API version used by the library to 8, from 7. Changes were made to BaseCredentials since version 8 of the API adds the AdService. Also, a bug was correct in the InfoServiceDemo which would cause this demo to fail if it was run in January.