Remove printed headers of all oauth2 queries

probably a debug committed by mistake in c2176d4e0365bb0764ff6962721053acaa1d1e39

see: https://github.com/sixohsix/twitter/commit/c2176d4e0365bb0764ff6962721053acaa1d1e39#diff-a11ddfeffc90fdbedb3d54d02a53bae8L63