[BUG #4831] Refactoring: Resolution independent CSS

* ToggleButton has no possibility to adjust its label size via JS. It used text ellipsis instead when state labels are too long.
[BUG #4831] Refactoring: Resolution independent CSS

* Extracted 2 new SCSS files "input" and "scroll" for global InputFields and ScrollComposite.
Minor update of qx.Mobile Toolbar Showcase.
[BUG #4831] Refactoring: Resolution independent CSS

* Removed qx.bom.AnimationFrame on updateSlot because it caused a bug.
[BUG #4831] Refactoring: Resolution independent CSS

* Added "_gradients.scss" which contains functions and mixins for creating cross-browser linear and radial gradients.
* Removed iOS6 SCSS files.
* Removed Android 2 SCSS files.
Reset iOS and Android css files to qx version 3.0
Merge "theme" SCSS into specific widget SCSS files of basic folder.
[BUG #4831] Refactoring: Resolution independent CSS

* Changed SCSS parts loading order.
[BUG #4831] Refactoring: Resolution independent CSS

* Added pxToEm function which enables the user to scale the application through root font size ($application-font-size as variable)
* Renamed SCSS mixin "pxToEm"  to "rem"
* Removed radial gradient functionality of "background" mixin, because backwards compatibility with old webkit syntax.
Updated frameworks "watch-scss" to use pyScss and to build the indigo.css
Minor layout bug on drawer's shadow.
Added background color to Mobile apps body, for changing Mobile Safaris Application background.
Refactored custom theme to refer to one theme color and 2 base colors.
Refactored custom theme to refer to one theme color and 2 base colors.
[BUG #4831] Refactoring: Resolution independent CSS

* Added pxToEm function which enables the user to scale the application through root font size ($application-font-size as variable)
Created a new qx.Mobile theme "Flat".
Created a new qx.Mobile theme "Flat".

* Updated Mobile Showcase to make it possible to switch between "Flat" and "Indigo"