Update key pair task:

(1) Add a new function to db_base to insert new records into openstack database
(2) Add a new function to utils/db_handlers/keypair to insert information to openstack database (call function in db_base)
(3) Before migrating a key pair, check: if the resource is contained in the target (if is contained, then ignore this key pair); whether the owner (an user) of the key pair on source cloud has been migrated successfully (if not, then stop migrating this key pair); and whether the user/owner of the key pair on the target cloud has already owned a key pair with the same name (if yes, than stop migrating this key pair)
(4) Update keypair task file: creating a new key pair data on the target cloud by inserting a record directly to the key_pairs table in target, rather than using nova client
Merge branch 'master' of https://github.com/Phoenix1708/OpenAcademy_OpenStack_Flyway