"Release" action

[maxi1134]

Is your feature request related to a problem? Please describe.
I am looking for a way to send a payload when pressing a button, and then a different payload when releasing it. To control a camera through rest_command.

Describe the solution you'd like
A "release" trigger for an action.
When releasing the button, something happens.

Describe alternatives you've considered
Not much else that can be done in this case I think, since the camera spins forever when receiving the "left" command, and then need to receive a "stop" command to stop.

Additional context
Let me know if you need anything!

[indykoning]

This pull request should take care of that: #360