about issue #70 : prepare to test this pr on cloud9

fix #70 ,it maybe cause by designing the ConfigSetting as an interface, work around it putting the _puppetinstace in to global

trying to fix this issue: 'Cannot create an instance of the abstract class 'FriendRequest'

no need to link wechaty because we have /node_modules/wechaty at root directory. and also that xvfb-chrome is already in path /wechaty/bin