first work on Firefox OS compatibility, some optimizations and enhancements

* added standard css properties
* removed duplicated css properties
* renamed ios6 css class to ios7
* slitly reformated css
* moved inline JS code to app.js (see http://programmers.stackexchange.com/questions/86589/why-should-i-avoid-inline-scripting)
* renamed "app" JS class to "App" and renamed public method "Init" to "init" (more standard)
* added "defer" to JS includes so they got executed after "onload" (faster layout) and removed onload event listener
* removed useless script type definition (html5 standard)
* cleaned up mixed double/single quotes in app.js