fix keyboard issues with kitkat and stock keyboard

This is a workaround for keyboard issues on kitkat. 

- The issue::
KitKat stock keyboard now supports suggestions for keywords starting from the current cursor position.
This used to happen only for new text being written and not for text that already existed in the textinput.
Cause of this The IME asks for text before cursor and after cursor only allowing editing of the text you provide here.

This work around is to set the text before, aft cursor to be empty allowing for deletion edition of text.

This is not a proper fix which would involve::
- passing the actual text before, aft cursor and
- calling the IMEs setComposingText(characters, cursor_pos) method on cursor updation in TextInput.