Unify actions endpoints (powerOn/powerOff) in a single endpoint

[r2dedios]

Join actions endpoints (powerOn/powerOff) in a single endpoint and specify the action as URL parameter or by adding a JSON body with the details of the action to run

[r2dedios]

Addressed in PR #252 and PR #264 — PowerOn/PowerOff unified under POST /actions with the operation specified in the request body.