GUI-325: Revamped Landing Page Filters

Implements https://eucalyptus.atlassian.net/browse/GUI-325

Notes:
- We can't filter instances by security group, scaling group, or load balancers since those are not properties of an instance object in Boto.
- We can't reliable filter images by platform since the platform property of an image either returns 'windows' or 'unknown' in Boto.
- We can't filter IPs by assignment since there is not such property to filter by in Boto.