I'd like to do some cleanup, which would facilitate further development. This includes:

• moving chart related code to a separate package (now it is in visualize)
• converting components created with React.createClass to es6 classes
• reorganize store and controllers to have all charts related things under 'charts'. Now we have 'charts' for charts ui, xyplot for xyplot charts, histogram for histogram charts, and tblstats for table statistics.

Fixed bugs

• missing chart mount action, when a chart is removed and then recreated on the same table
  Steps to reproduce: load a table (default scatter plot created), create histogram, delete scatter, create new scatter.
  The last scatter did not produce mount action, and the plot was not tracking table changes, like filter.

• undefined shows as a label when no server call is necessary
  Steps to reproduce: load table (default scatter created), clear options and choose the same columns , click apply.
  "undefined" are shown as axis labels