Make sure that fee calc uses decimals properly.
Use dev version of gunicorn.

Fixes a hard to track down bug that was affecting us, see the links.

Because I am now paranoid, log exceptions during Flask request teardown.
Make sure limits are  properly treated as decimals.
Validation mustn't be sent as form-encoded.

wasipaid can (currently?) not handle such a mis-labeled request,
and I believe due to a bug in requests that content type is chosen
by default when bytes are given, which is the case on Python 3.
Tests were broken due to recent changes.
Add Google Analytics code.
Remove uwsgi ini file, no longer used.
Run on Python 3 has always intended.