Ignore annoying OS X files
Switch back to the none-nested default style definition

Instead of specifying the element states within the default
style definition (the "style" property), a property "states"
will be introduced which holds the different state styles.
This removes the unnecessary +1 nesting when specifying the
default style.
Add getter for the controller
Remove unimplemented method
Remove unused methods (to be replaced with json system friendly versions)
Make it possible to set background image size and origin via json gui system
Clean up LayoutDefinitionLoader
Add utility method to retrieve only an Asset's data
Implement style classes (i.e. reusable style definitions)