Added 4 new functions to ec2 module
Added 4 new functions to ec2 module

Added the following functions:
* terminate_instances()
* release_public_ip()
* delete_keypair()
* delete_security_groups()

Signed-off-by: Shashank Sahni <48273395e0436587f8f1beebda52d256c947abb2@gmail.com>

siel-iiith/MultiStack,siel-iiith/MultiStack