Adds a schedule_json view which provides a /schedule/conference.json endpoint, of the kind that Carl uses for producing conference videos.

Also useful to feed into mobile schedule apps!

It is expected that someone might have to customize this for their own installation (PyCon Canada definitely did, with modifications to some of the models).
adds a schedule json endpoint. based on @taavi's PR #45 with some changes from the @pyohio/pyohio repo
flake8 fixes
added cancelled element to json, used taavis start/end props
flake8 fix
Merge pull request #62 from codersquid/json_endpoint

Adds a schedule_json view