Pyatv

**Changes:**

* Add device_id
* Remove developer commands

**Changes:**

* Support AirPlay device authentication
* Support arrow keys (left, right, up, down)
* Support scanning for Apple TVs with home sharing disabled
* Support for shuffle and repeat modes
* Support for "stop" button
* Handle additional media kinds
* New "hash" function in Playing API
* Support python 3.6
* Bump aiohttp to 1.3.5 and support 2.0.0+

*atvremote:*

* Multiple commands can be given to atvremote
* Doing "atvremote commands" requires no device and is a lot faster
* All commands now listed with "atvremote commands"
* New "help" command in atvremote
* Fix atvremote exit codes

**Notes:**

* play_url has moved to the new airplay module and no longer
accepts start position as required argument. This is a
breaking change!

*Other:*

* Upgrade test tools (pylint, flake, etc.)
* Added documentation to readthedocs

**Changes:**

* Allow custom pairing guid when pairing

**Notes:**

* By default, a random pairing guid is now generated when calling
pyatv.pair_with_apple_tv.

**Changes:**

* Always trigger one push update when starting

**Changes:**

* Support for push updates
* Fast auto discovery for single device
* Nicer output in "atvremote playing"
* Pairing improvements
* Unpin external dependencies

*Other:*

* Easier version management (internal)
* Code quality improvements (quantifiedcode)

**Changes:**

* Added new function: artwork_url
* aiohttp bumped to 1.3.1