CloudSigma2 ComputeService and SecurityGroupExtension

* Added the ComputeService implementation
* Added the SecurityGroup extension
* Added the San Jose region
@nacx, @demobox: hmm, it fails for me

    this.rules = rules == null ? new ArrayList<>() : rules;

Error:

    jclouds-labs/cloudsigma2/src/main/java/org/jclouds/cloudsigma2/domain/FirewallPolicy.java:[140,34] incompatible types
    [ERROR] required: java.util.List<org.jclouds.cloudsigma2.domain.FirewallRule>
    [ERROR] found:    java.util.List<capture#1 of ? extends java.lang.Object>