Stream-python

* Added support for read-only tokens

* Added support for extra data for follow actions

* Bugfix, mark_seen and mark_read now work

* Added location support to reduce latency

* Additional validation on feed_slug and user_id

* Breaking change: New style feed syntax, client.feed('user', '1') instead of client.feed('user:3')
* Breaking change: New style follow syntax, feed.follow('user', 3)
* API versioning support
* Configurable timeouts
* Python 3 support