Apply `futurize --stage-2` Python 2/3 compatibility transformations.

These changes specifically require the use of the "future" library.

Support display of donation count in fundraiser.

Allow display of a donation count in the fundraiser pages, with an
optional threshold that must be met before it's displayed.

Function to compute how far to the goal we are.

This is also inserted by the Javascript code as well, but no reason we
can't compute it server side, too.

Initial hack at a fundraising goal application.

This simple application will simply store the code name and the to goal
of each fundraiser. The so_far number will likely just be updated by
some external script, modifying the appropriate entry in the SQL
database.