Reset scrollLeft when setSoftWrapColumn is called

When the scroll view is scrolled and overflow-x is set to 
'hidden' the scroll view renders wrong. Setting scrollLeft to 0 fixes
this problem. I'm unhappy with this solution, but it was a
simple way to get the scroll view to update its layout.

Closes #137

src/app/editor.coffee

@@ -590,6 +590,7 @@ class Editor extends View
     @setSoftWrapColumn(softWrapColumn) if @attached
     if @activeEditSession.getSoftWrap()
       @addClass 'soft-wrap'
+      @scrollView.scrollLeft(0)
       @_setSoftWrapColumn = => @setSoftWrapColumn()
       $(window).on "resize.editor-#{@id}", @_setSoftWrapColumn
     else