CMakeLists.txt: require python 2.7
CMakeLists.txt: require python 2.7

https://bugs.freedesktop.org/show_bug.cgi?id=36680

Reviewed-by: Alexandr Akulich <ad71d6ef874ccc09e1a69fe0dd6443b72073e71a@gmail.com>

TelepathyQt/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyQt/telepathy-qt