add missing import
remove unused imports
use python logging library instead of print statements
authorize.net: log request dict in addition to query string
Fixing three failing tests / remove duplicate.

Three of the tests were failing because there was a hard-wired expiration date of 2012 that was causing the is_valid() check to fail.

I've set up the tests to use a relative delta so that the tests will always pass no matter what your system date is.

One of the tests was also a copy-paste error and has been removed.

All tests are passing now. On to some TDD on the Authorize library.
Added Travis configuration. :sparkles: Add python-dateutil dependency.
Travis config
Warn only for flake8 check
Only check coverage on paython package
Added travis image.
travis round 2

lets see if this works
Unknown AVS+card OK; use official response status

The code has also been reformatted to be more visually consistent
(mostly removing stray spaces)