added onShow and onHide
Added callbacks and a method to get the active screen
Added a check
Merge branch 'development' into 232-add-logic-to-screens

Conflicts:
	js/modules/glue/director.js
fixed callbacks that were missing (happened because of merging) and added builds
Merge branch 'development' into 232-add-logic-to-screens

Conflicts:
	build/glue.js
	build/glue.min.js
Merge pull request #234 from spilgames/232-add-logic-to-screens

#232 add logic to screens