Establish the supported importable interface

* Consumers of this client should not depend on being able to import
  any module other than glanceclient and glanceclient
* The only attributs of the glanceclient module are Client
  and __version__
* The attributes of the glanceclient.exc modules have yet to be
  locked down
* glanceclient.common.exceptions was replaced with a placeholder
  module until consumers of it are updated

Change-Id: Iea9648cd06906d65764987c1f2ee5a88ebeee748

glanceclient/common/utils.py

@@ -18,7 +18,7 @@ import uuid
 
 import prettytable
 
-from glanceclient.common import exceptions
+from glanceclient import exc
 from glanceclient.openstack.common import importutils
 
 
@@ -67,23 +67,23 @@ def find_resource(manager, name_or_id):
     try:
         if isinstance(name_or_id, int) or name_or_id.isdigit():
             return manager.get(int(name_or_id))
-    except exceptions.NotFound:
+    except exc.NotFound:
         pass
 
     # now try to get entity as uuid
     try:
         uuid.UUID(str(name_or_id))
         return manager.get(name_or_id)
-    except (ValueError, exceptions.NotFound):
+    except (ValueError, exc.NotFound):
         pass
 
     # finally try to find entity by name
     try:
         return manager.find(name=name_or_id)
-    except exceptions.NotFound:
+    except exc.NotFound:
         msg = "No %s with a name or ID of '%s' exists." % \
               (manager.resource_class.__name__.lower(), name_or_id)
-        raise exceptions.CommandError(msg)
+        raise exc.CommandError(msg)
 
 
 def skip_authentication(f):