Update internal data array when using setData (fixes #213).

lib/morris.grid.coffee

@@ -97,6 +97,8 @@ class Morris.Grid extends Morris.EventEmitter
   # Update the data series and redraw the chart.
   #
   setData: (data, redraw = true) ->
+    @options.data = data
+
     if !data? or data.length == 0
       @data = []
       @raphael.clear()

morris.js

@@ -151,6 +151,7 @@
       if (redraw == null) {
         redraw = true;
       }
+      this.options.data = data;
       if (!(data != null) || data.length === 0) {
         this.data = [];
         this.raphael.clear();