Adds flavor_id in the nova_notifier

The instance_type_id is the primary key stored in Nova's instance_types table.
The flavorid is the public id provided at the creation of the flavor.

When we create an instance using the flavor m1.tiny, we can see instance
info contains below keys:
    "instance_type_name" :"m1.tiny"
    "instance_type_id": 2,
Actually, the "m1.tiny" flavorid should be a string '1'. Considering
changing the id's tpye maybe cause confusion with the already saved old
data, add flavor_id to the flavor dictionary.

The instance_ref has all the flavor infomation, not need to get flavor
info from DB again.

Change-Id: I5bd19b2bc2f874d31fd4609306c24e0f51517281
Closes-Bug: #1273638
Merge "Adds flavor_id in the nova_notifier"