failing test for #364
 record credit card failures in the DB (closes #364)
update test dependencies
remove unused variable detected by pyflakes
upgrade Aspen to 0.36

fixes #2984 and #3004
actually, remove the entire function, we don't use it anymore
don't consider suspicious users as ANON (fixes #2786)
Merge pull request #3019 from gratipay/aspen-0.36

Upgrade Aspen to 0.36
Merge pull request #3021 from gratipay/suspicious-not-anon

Allow suspicious users to log in
Merge pull request #3017 from gratipay/update-test-deps

Update test dependencies
Bump version to 1749
Add test for error result being recorded
Merge pull request #3011 from gratipay/record-cc-failures

Record credit card failures in the DB
work around honcho's problem with python 2.7.9
Merge pull request #3028 from gratipay/honcho-hack

Work around honcho's problem with python 2.7.9
refactor some billing code
update the tests
increase test coverage by going through the simplates