adds wifi events from js

Goes with https://github.com/tessel/wifi-cc3000/pull/1
you're right, it should be in the callback after disconnect. Though we also run into the scenario of:
1) get a command to initiate a connection
2) orange led starts blinking
3) disconnect command is issued because of a timeout

I'm not 100% positive that there is a disconnect callback given that we were never connected in the first place. I'll test that.