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

https://issues.apache.org/jira/browse/JCLOUDS-496

This contains the changes in https://github.com/jclouds/jclouds/pull/439 for master. In 1.7.x the duplicated methods in the `NovaTemplateOptions` class were deprecated and this PR removes them, but keeping the particular logic for not allowing empty security groups.