JCLOUDS-661: Add ability to create single port firewall rule from Securi...

...tyGroupExtension

added check for to and from port being the same
added test in BaseSecurityGroupExtensionLiveTest

fixes https://issues.apache.org/jira/browse/JCLOUDS-661
This isn't really in the scope of this change, I know, but why this check here? If we're verifying the "to" port, shouldn't we also check the "from" port? Especially since toPort > 0 wouldn't seem to immediately imply fromPort > 0?