Fix in branch for ST3

For the issue [#7 - Toggle only works on first run] (https://github.com/disq/HighlightWhitespaces/issues/7) I did some changes which seem to work on Sublime Text 3. It seems the hws_settings are not getting picked.

Following are the changes in this patch:
1.  Fix for issue #7 - Toggle only works on first run .
2.  Changed the space highlighting on even one space as against prior requirement on 2 spaces, as I needed that for my usecase.