BUG: Only initialize a PlateViewer() on "create"

Closes biocore#567, and addresses one of the two "warts" needed before my
fork can be merged back in (that will take care of biocore#354)

labcontrol/gui/static/js/plate.js

@@ -115,7 +115,6 @@ function change_plate_configuration() {
   } else {
     // reset the container before updating the grid configuration
     $('#plate-map-div').empty().height(0);
-    pv = new PlateViewer('plate-map-div', undefined, undefined, $opt.attr('pm-data-rows'), $opt.attr('pm-data-cols'));
     // Enable the plate create button now that a plate config is selected
     $('#createPlateBtn').prop('disabled', false);
   }

labcontrol/gui/static/js/plateViewer.js

@@ -255,14 +255,6 @@ PlateViewer.prototype.initialize = function (rows, cols) {
   // don't select the active cell, otherwise cell navigation won't work
   this.grid.setSelectionModel(new Slick.CellSelectionModel({selectActiveCell: false}));
 
-  // TODO: This function is called twice every time an event happens, and that
-  // is because this binding is applied twice (because this initialize()
-  // function is called twice). This is likely worth addressing -- there are
-  // multiple ways to circumvent this -- but I'm not sure what would be best.
-  //   Idea 1: add this binding at the bottom of the plate HTML template
-  //   Idea 2: add logic to detect if this binding already exists (buggy?)
-  //   Idea 3: ignore this, and just accept that the callback will be called
-  //          twice (...is this intended?)
   $('#multiSelectCheckbox').on('change', function() {
     // In this callback function, "this" is the m.s. checkbox's <input> element
     // "that" is defined as this (see the start of this function), which lets