add instructions about setting up track/untrack to the README
tweaks
start making it python 3 compatible
use a better (and python3 friendly) rfc3339 library
use run_flow instead of run, to avoid dependency on flags library

see
http://stackoverflow.com/questions/20369876/how-to-use-run-flow-in-google-calendar-api
update and reformat the package requirements
Merge pull request #3 from xrchz/master

making it work on my machine