JCLOUDS-496: Use the security groups options in the portable TemplateOptions

https://issues.apache.org/jira/browse/JCLOUDS-496

This PR deprecates the duplicated methods in the provider specific NovaTemplateOptions and updates the code to use the portable method.
[minor] Just spacing: `return getGroups().isEmpty() ? Optional.<Set<String>>absent() : Optional.of(getGroups());`