refactor file-input: Add "change" and "value" parameters

"Change" parameter as callback to return the dom input to the function
"value" parameter to handle dynamic values and automatically set the value if needed to
fix file-input: Fix indentation to the Allman style
docs file-input: Add comments for better comprehension of the value attribute
fix file-input: add "newValue" and "oldValue" to the parameters returned in the change callback

Before, we are using a non-conform way to pass values in callback.
By adding brackets in the callback, we switch to the angular-way and return two more values : the new input value and the old.