Rename resize-flavor subcommand to resize-instance

The trove resize-flavor <instance> <flavor_id> subcommand actually
changes the flavor of an instance, not the size of the flavor itself.

To improve clarity, the resize-flavor subcommand was renamed as
resize-instance.

To avoid backward compatibility issues, marked deprecated the
resize-flavor subcommand while we introduce the new resize-instance
subcommand.

DocImpact: This potentially affects any user scripts that may
exist.  Any instructions like:
'trove resize-flavor <instance> <flavor_id>'
should be changed to:
'trove resize-instance <instance> <flavor_id>'

Change-Id: Ie801d5632383b67c3f777487f4b6bc608b4a69e8
Closes-Bug: #1324719

troveclient/v1/instances.py

@@ -147,7 +147,7 @@ class Instances(base.ManagerWithFind):
         self._action(instance_id, body)
 
     def resize_instance(self, instance_id, flavor_id):
-        """Resize the volume on an existing instances."""
+        """Resizes an instance with a new flavor."""
         body = {"resize": {"flavorRef": flavor_id}}
         self._action(instance_id, body)
 
@@ -168,9 +168,6 @@ class Instances(base.ManagerWithFind):
                          "instance")
 
 
-Instances.resize_flavor = Instances.resize_instance
-
-
 class InstanceStatus(object):
 
     ACTIVE = "ACTIVE"

troveclient/v1/shell.py

@@ -273,8 +273,21 @@ def do_create(cs, args):
            help='New flavor of the instance.')
 @utils.service_type('database')
 def do_resize_flavor(cs, args):
-    """Resizes the flavor of an instance."""
-    cs.instances.resize_flavor(args.instance, args.flavor_id)
+    """[DEPRECATED] Please use resize-instance instead."""
+    do_resize_instance(cs, args)
+
+
+@utils.arg('instance',
+           metavar='<instance>',
+           type=str,
+           help='ID of the instance.')
+@utils.arg('flavor_id',
+           metavar='<flavor_id>',
+           help='New flavor of the instance.')
+@utils.service_type('database')
+def do_resize_instance(cs, args):
+    """Resizes an instance with a new flavor."""
+    cs.instances.resize_instance(args.instance, args.flavor_id)
 
 
 @utils.arg('instance',