Uninstall xctool on Travis before installing it again
Uninstall xctool on Travis before installing it again

Attempt to fix broken build because of "Error: xctool-0.1.7 already installed".

https://travis-ci.org/mysterioustrousers/MTDates/builds/10717206
mysterioustrousers/MTDates,jeffaburt/MTDates,Alex9779/MTDates