Button Overrides Part 3

What's new:

Service call button overrides

As discussed long ago in #6, the option to call Home Assistant services directly through the YAML config has finally arrived!

Details can be found here:
https://github.com/PRProd/HA-Firemote#button-overrides

Special thanks to @ghvader, @toddsay, @clinds34, @michaelhenningersrb, @craigrouse, and @broyuken for this additional override request, and their patience with me to finally get it done.

Additional buttons on Shield Remote

NVIDIA Shield style 1 remote now includes the secret volume control buttons in the "spine" area between the "wings" on the bottom of the remote. Click around and you might find them.

Full Changelog: v2.0.2...v2.0.3