Pusher

- [CHANGED] Utilities no longer escape non ascii characters.

- [ADDED] Allow Client to accept float as a timeout
- [CHANGED] the maximum event payload size permitted by this library has been increased. This change affects the library only: the Channels API still maintains a 10kb size limit and will return an error if the payload is too large.

- [ADDED] terminate_user_connections method

* [FIXED] An issue where payload size wasn't being calculated properly

* [FIXED] Expired root certificates

* [ADDED] option `encryption_master_key_base64`
* [DEPRECATED] option `encryption_master_key`

* [REMOVED] old support for Push Notifications, see https://github.com/pusher/push-notifications-python