Fetches all events labelled "Datebot" between now & 6 months from now.

* get_future_dates in Google Oauth helper file connects to Gcal API and
requests events between now & 6 months using timeMin and timeMax params
* gcal_format in Time helper file formats dates using Google's preferred
format ("%Y-%m-%dT%H:%M:%SZ"), where "Z" means GMT.
* converts dates in request to GMT.