Moved getGlobal from Game to GameLoop

- It needs a gameStage parameter now
- Added tests in GameLoopTest
- Added parameter checking to Stager.setDefaultGlobals
Added getProperty, defaultProperties

- Set default properties with Stager.setDefaultProperties
- Look up a property with GameLoop.getProperty
Updated Stager's state getter/setter for defaults
Merge branch 'merginben' of github.com:nodeGame/nodegame-client into merginben