Add client property for common.base.Manager

The latest oslo-incubator.apiclient code assumes resource manager has
property named client, but ceilometerclient has named that property
to api, which will cause problem when we sync with oslo-incubator.

This patch simply uses client as an alias of api.

Change-Id: I90c5ff10309ff7ad3fb634274e16c26ec8e6a1a2

ceilometerclient/common/base.py

@@ -49,6 +49,11 @@ class Manager(object):
     def __init__(self, api):
         self.api = api
 
+    @property
+    def client(self):
+        """Compatible with latest oslo-incubator.apiclient code."""
+        return self.api
+
     def _create(self, url, body):
         body = self.api.post(url, json=body).json()
         if body: