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