Optional Column Field
======================

Column field in portlet should be made optional. If the value is missing,
assume single group and count all resources.

This is needed for the pie chart view

List of available row/column fields, chart type, & stats type
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Currently they are kindof hardcoded, need to be configurable somewhere
or through some mechanism so that we can easily add more through other
products

A possible implementation is through a control panel view
