CloudSigma2 ComputeService and SecurityGroupExtension

* Added the ComputeService implementation
* Added the SecurityGroup extension
* Added the San Jose region
Same as commented above. The `!` operator negates a range, and returning `0.0.0.0\0` would also include the IPs that should be out of the rule. This must be changed, together with the port parsing, to return a rule (or a set of rules) that properly matches what is defined in the given `FirewallRule`.