Gui 1239 VPC support for Launch More Like This

https://eucalyptus.atlassian.net/browse/GUI-1239

This branch is built on top of GUI-1162. Do not merge this branch before GUI-1162 is merged.

There's a lot of code duplicated in the run_instances() call in this block and in the "if vpc_network is None" block below.  We should use the if/else condition to build up a list of params as a dictionary and pass that to the run_instances() call via **params.  See the last few lines of revoke_all_rules() in views/securitygroups.py for an example.