Add instance name as parameter to CLI

Allow CLI to take instance name as well as instance id for
sub-commands where instance can be specified. This commit
does not include the metadata-* commands as the backend for
that feature isn't merged. The spec will be adjusted to
reflect that they commands will be out of scope.

Affected sub-commands are:
backup-create
backup-list-instance
configuration-attach
configuration-default
configuration-detach
create (just for --replica_of)
database-create
database-delete
database-list
detach-replica
delete
resize-flavor
resize-instance
resize-volume
restart
root-enable
root-show
update
user-create
user-delete
user-grant-access
user-list
user-revoke-access
user-show
user-show-access
user-update-attributes

Unit tests were added to test passing in an instance object
for the affected sub-commands. A new set of unit tests were
added for databases.py (doesn't look like any existed before).

Change-Id: I5554a7d423990ff9cb24437a893d90d212b022b1
blueprint: add-instance-name-to-cli
Merge "Add instance name as parameter to CLI"