Changing vmName to amazon style generation
set display_name and host_name equals to instance_name
removing logic on display name of vms
Add change on EC2Engine to use the custom displayName
Fix logic (comment #cb376dd)
reverting the changes on the EC2Engine to port to cs4-extensions before
Adding rule to set display name equal to the instance name when it is empty
Merge branch 'instance_identifiers' into 4.2