Switch to RobotJS instead of keysender

[MrFastDie]

Hey,

could you consider switching from keysender to RobotJS? The main problem with keysender is that its windows only (this references #43 )

I'd also like to use this bot while on vacation using my mac or linux notebook. If you're open to it I would try to implement the change and open a PR. If not please let me now so I dont waste any of my time.