added 'refresh' method to textinput

reference to issue #5708
and previous pull request.
#5766
added 'refresh' method to textinput.
added a _private method '_refresh' and called same from create and refresh.

demo test page :http://jsbin.com/edidil/7/ [Got various combinations of input fields and button to refresh input.]

demo test page : http://johnchacko.net/samples/textinputs.html