Pepare for v1.2 release.

Reviewed in https://codereview.appspot.com/10841043/.
diff --git a/oauth2client/__init__.py b/oauth2client/__init__.py
index 7e4e122..ac84748 100644
--- a/oauth2client/__init__.py
+++ b/oauth2client/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "1.1"
+__version__ = "1.2"
 
 GOOGLE_AUTH_URI = 'https://accounts.google.com/o/oauth2/auth'
 GOOGLE_REVOKE_URI = 'https://accounts.google.com/o/oauth2/revoke'