Make ManagerWithFind abstract and fix TokenManager

ManagerWithFind requires list() method in its descendants.
Make it abstract and fix its improper descendant TokenManager
that do not implement list().

Change-Id: I83ae47d894c02d5cd1eb0da437dd05796d0b0160
Fixes: bug #1180393

keystoneclient/base.py

@@ -18,6 +18,7 @@
 Base utilities to build API operation managers and objects on top of.
 """
 
+import abc
 import urllib
 
 from keystoneclient import exceptions
@@ -116,6 +117,13 @@ class ManagerWithFind(Manager):
     """
     Like a `Manager`, but with additional `find()`/`findall()` methods.
     """
+
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
+    def list(self):
+        pass
+
     def find(self, **kwargs):
         """
         Find a single item with attributes matching ``**kwargs``.

keystoneclient/v2_0/tokens.py

@@ -18,7 +18,7 @@ class Token(base.Resource):
         return self._info['token'].get('tenant', None)
 
 
-class TokenManager(base.ManagerWithFind):
+class TokenManager(base.Manager):
     resource_class = Token
 
     def authenticate(self, username=None, tenant_id=None, tenant_name=None,