Fix the height setting of the scrollWrapper

* set both max-height and height on the tableWrapper div
* listen for a resize on the tableWapper and if so calculate the scroller
  height to be the tableWrapper height - header.  The listener is
  debounced if happening too often.
* remove the max-height on the first table and set limit to 5 on example
* add a bottom border for the scroller for a more polished look
Merge pull request #40 from jadrake75/selection-mixin

Fix the height setting of the scrollWrapper