Change dist resource to use DataField.dist method

The previous dist resource has been moved to ./dims/ for "dimensions"
since it supports arbitrary number of fields (dimensions) to
aggregate on.

Fix #203

Signed-off-by: Byron Ruth <b@devel.io>
Consider moving this comment closer to the code it relates to. Putting it directly above `result = []` led me to think it related to that line which obviously just initializes result but has nothing to do with the label.