Adapters to patch jQuery, PrototypeJS and YUI3 methods

Adds adapters to patch:

 - jQuery `$.fn.val`
 - Prototype `Form.Element.getValue` and `$F` by extension
 - Prototype `Form.Element.Methods.getValue`
 - YUI3 `get` method (from the `Node` module)

The adapters will return the empty string if the polyfill is active. If it's not active they delegate back to the real method.

Also renames build output files so file names are all lower case.