Implemented EventEmitter.once() and EventEmitter.removeListener()
Implemented EventEmitter.once() and EventEmitter.removeListener()

IoT.js-DCO-1.0-Signed-off-by: Ilyong Cho ily.cho@samsung.com

qdk0901/iotjs,gertom/iotjs,rstr74/iotjs,VandeurenGlenn/iotjs,qdk0901/iotjs,diorahman/iotjs,gertom/iotjs,bozzmob/iotjs,rstr74/iotjs,diorahman/iotjs,wateret/iotjs,Vincent2015/iotjs,qdk0901/iotjs,bozzmob/iotjs,kod3r/iotjs,lemmaa/iotjs,wateret/iotjs,diorahman/iotjs,chunseoklee/iotjs,kod3r/iotjs,wateret/iotjs,kod3r/iotjs,lemmaa/iotjs,rstr74/iotjs,chunseoklee/iotjs,lemmaa/iotjs,ILyoan/iotjs,Vincent2015/iotjs,ILyoan/iotjs,chunseoklee/iotjs,Vincent2015/iotjs,ILyoan/iotjs,VandeurenGlenn/iotjs,gertom/iotjs,bozzmob/iotjs,VandeurenGlenn/iotjs