Add detection for BlackBerry 10 devices

This adds support for BlackBerry 10 devices, which removed the "BlackBerry" token from the user agent. This adds a new OS test `bb10` (useful for directing users to BlackBerry World), sets the `os_string` to "BlackBerry 10" and since the device models are included in the user agent, offers the model name in the `device_name`. Additional reference: http://devblog.blackberry.com/2012/08/blackberry-10-user-agent-string/

Fixes #79