Tweak volume commands and add k=v argparse action

Basic cleanups:
* change metadata to property
* add new KeyValueAction to parse the property options
* multiple properties can be set using multiple --property args
* consistent formatting
* do lookups for volume args

Change-Id: Ib6c43f01ad46b395aee8c61e886f42e2a5f5573e

openstackclient/common/parseractions.py

@@ -0,0 +1,34 @@
+#   Copyright 2013 OpenStack Foundation
+#
+#   Licensed under the Apache License, Version 2.0 (the "License"); you may
+#   not use this file except in compliance with the License. You may obtain
+#   a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#   License for the specific language governing permissions and limitations
+#   under the License.
+#
+
+"""argparse Custom Actions"""
+
+import argparse
+
+
+class KeyValueAction(argparse.Action):
+    """A custom action to parse arguments as key=value pairs.
+    Ensures that dest is a dict
+    """
+    def __call__(self, parser, namespace, values, option_string=None):
+        # Make sure we have an empty dict rather than None
+        if getattr(namespace, self.dest, None) is None:
+            setattr(namespace, self.dest, {})
+
+        # Add value if an assignment else remove it
+        if '=' in values:
+            getattr(namespace, self.dest, {}).update([values.split('=', 1)])
+        else:
+            getattr(namespace, self.dest, {}).pop(values, None)