EUCA-8494 add account_id field to resources
Merge branch 'dev/ethomas/EUCA-8494' into testing
Map request from SYSTEM user to Eucalyptus/Admin for backend requests. Fixes EUCA-8563

Additional exception handling and lookup logic for mapCredentials() in the Walrus and S3 providers.
Merge remote-tracking branch 'origin/dev/sjones/EUCA-8502' into testing