Add drag-and-drop to Excel

Entire buckets can be dragged and dropped into Excel

I think we could present this as our solution to reports and statistics.

Instad of making our own inflexible, crappy looking  bar graph tab, we
just let users drag into Excel and do their own analysis.  They can take
whatever columns they actually care about, and compute whatever statistics
they actually need. Afterwards, they can format it however they need to
(ex. for a final report or a presentation or something) using familiar
tools.

Using an external program has disadvantages, such as the time it takes
to export over and over again if data changes, but the fact that you can
export using swag and drop makes it easy enough that it probably doesn't
matter.

Change-Id: Ic947869b6252dad992a3b8f29952cbda7986fc50