Refs. #17. Print errors codes and message on other exceptions.

This includes TimeoutErrors, ProtocolErrors and other general Exceptions.
Also print a message when the user enters a wrong command.
Refs. #8. Minor changes for codebase on python 2 and 3.

Changed print statements to the print function, and adjust imports to work on pytohn 2 and 3.
Refs. #15. Add initial version of the whitelist webservice.
Refs. #15. Style improvements.
Change default log location and add pyzor to requirments.
Refs. #15. Add documentation about the whitelist service.
Add a success message when the request was sent.
Add executable permission to application.py
Improve forwarder test coverage.
Refs. #23. Do reports and whitelists in a single step for MySQL.

Each server engine can now define two methods ``report`` and
``whitelist`` which accepts a list of digests for which the report
and whitelist count should be incremented. If the engines supports
this it must have the ``handles_one_step`` argument set to True.

Implement this for the MySQL engine using INSERT ... ON DUPLICATE KEY
UPDATE, and executemany for batches.

Also add some functional tests around this functionality and fix
the existing unittest.