CloudSigma2 ComputeService and SecurityGroupExtension

* Added the ComputeService implementation
* Added the SecurityGroup extension
* Added the San Jose region
Yes, it is intentional. The taskname is the name of the script that will be created in the target node, so it is being set if the user has not explicitly set one. The code in this method, is just a copy of the code in the parent class but removing the authorize public key statement, as we're using the provider key pair features.