CIMI: Use #collection_class_for helper for all collections in client
Added 'stop' functionality to ec2 driver

Added new state, added stop method, removed alias.
Added start functionality to stopped EC2 instances
Fixed instance state conversion. Tested EBS instance for start/stop/reboot. Works fine
Fixed formatting
Modified 'stop_instance' method to check if instance root type is ebs or instance_store. If ebs -- stop instance otherwise destroy instance
Cleaned up code
Added note
EC2 driver - modify instance actions depending on transient root (ebs/root_store)

related to https://github.com/deltacloud/deltacloud-core/pull/44
EC2 driver - Fix for determining instance_actions on ebs/root_store instances

https://github.com/deltacloud/deltacloud-core/pull/47