GUI-577: Add filters for launch configs landing page

Implements filters for the launch configs landing page for https://eucalyptus.atlassian.net/browse/GUI-577

@JMoLo: Note that although the spec calls for the filters to be by availability zone, instance type, root device type, security group, and scaling group, we can only implement filters for instance type and security group per what's available in the data set returned from Boto.  We can also filter by key pair, so that field has been added to the filters.