Adding a .revoke() to Credentials. Closes issue 98.

Reviewed in https://codereview.appspot.com/7033052/
diff --git a/oauth2client/__init__.py b/oauth2client/__init__.py
index 4802e90..13d949f 100644
--- a/oauth2client/__init__.py
+++ b/oauth2client/__init__.py
@@ -1 +1,5 @@
 __version__ = "1.0"
+
+GOOGLE_AUTH_URI = 'https://accounts.google.com/o/oauth2/auth'
+GOOGLE_REVOKE_URI = 'https://accounts.google.com/o/oauth2/revoke'
+GOOGLE_TOKEN_URI = 'https://accounts.google.com/o/oauth2/token'