Analysis types for Pie Chart!

Addresses issue #1799 per @fgmart 's request.

**Change summary:**

1.  The code that drew the "Tools" control div in Bar Charts (including Sort Field, Analysis Type, and Logarithmic Y Axis) has been moved to the BaseVis class as the drawToolControls method.
2.  Pie Charts and Bar Charts now call this function to draw their "Tools" control div with two flags, which determine whether or not the Sort By controls and Logarithmic Y Axis Controls are drawn, respectively, since these controls only pertain to Bar Charts.
3.  Added a getGroupedData function to BaseVis that returns the data to be displayed in the Highcharts series for Bar Charts and Pie Charts.  The exact data that is returned is dictated by the chart's analysis type, and the data is returned in two different formats for bar charts and pie charts for compatibility with existing code.
4. Removed existing code to compute the data to be displayed for Pie Charts, as it was not conducive to implementing analysis types.
I take back what I said earlier about vis specific comments. This one is OK.