Expose serialized graph via API for Fuel for OpenStack

Handler for GET request that will provide data that is prepared for task-based-deployment. Details are provided in specification.

L2/L3 Network checking for Fuel for OpenStack

This is a blueprint for checking all the communications between nodes before provisioning/deployment.

Improvements of fuel network checks for Fuel for OpenStack

In my opinion fuel needs clear interface that wil allow easily extend network checks or any other, that require to run on openstack nodes. Pls see attachment for detailed motivation.

Extandble verification handler for nailgun and commands for cli for Fuel for OpenStack

Create handler for running arbitrary verifications on cluster. After discussion decided to use separate handlers for each verification task RETURN jsonified Task object it will be invoked from cli, smth like: fuel verify multicast --env 1 fuel verify l3 --env 1