Merge pull request #2 from fusijie/master

Merge branch 'master' of https://github.com/Wu-Hao/TankMultiplayer
initial player collision
optimizing game update logic
Merge branch 'master' of https://github.com/Wu-Hao/TankMultiplayer

Conflicts:
	Classes/GameScene.cpp
	proj.ios_mac/TankMultiplayer.xcodeproj/project.pbxproj