Add wifi toggle for kobos

This does not work yet. I mean NetworkMgr:promptWifiOn() is not called and the message:
 Error occurs when login: plugins/evernote.koplugin/EvernoteOAuth.lua:208: Network is unreachable
 is displayed.

wifi script works ok when called from shell.

I also cleaned a little bit kobo scripts, since koreader just support touch devices there is no need to differenciate between freescale and ntx platform