GUI-325: Landing Page Filters Redux

Implemented all remaining requested filters on the landing pages.  See comments in the prior pull request at https://github.com/eucalyptus/koala/pull/156

Notes:
- We're only able to filter instances by a single security group since the "group-name" filters param passed to get_only_instances() only appears to accept a single value.
- We're not implementing the ELB filter on the Instances landing page per implementation restrictions.