GUI 811 - Allow launch configs and instances to be filtered by keypair option "None" + security group filter fix on the launch config landing page

https://eucalyptus.atlassian.net/browse/GUI-811

This branch is built on GUI-1328 due to the need for the fix made in the currently merge-pending branch.

Fixed the launch config landing page's keypair filter to accept "None"
Fixed the instance landing page's keypair filter to accept "None"
Fixed the launch config landing page's security group filter to use IDs instead of names.
The AWS API does not support the instances to be filtered by an empty keypair name. The instances are filtered by keypairs in the "filter_items" function instead.