test now works

I actually tried to fix the W504/W503 errors, but failed ungracefully.
Also there was no help online, nor was there something that would
automatically fix it.

No, I am not ever again spend time trying to pacify linters, they
have to fix it automatically.

Fixes #394

For some reason, I didn't trust the existing one as it tests that code
more indirectly.

Related to #160

Conflicts:
	README.md
	requirements.txt
	setup.py

It represents the latest state on github, which should be better than
what's installed by default.

[skip ci]

tox https://pypi.python.org/pypi/tox is a thin wrapper around virtualenv
which let you craft a fresh python environement to execute command in.

It creates the env with virtualenv, install dependencies, run python
setup.py install in it and then execute whatever command you want it to
do and report status.

To do so I simply:

- listed tests dependencies in test-requirements.txt (which are just
  nose and mock)
- provide a tox.ini file which describe how to install the dependencies
  and execute nosetests
- added the module 'coverage' to the list of test dependencies

To run tests simply:

 pip install tox && tox

That will execute the test command 'nosetests' using python2.6 and then
python 2.7.

The additional env 'cover' can be run using: tox -ecover.

As relative paths are used througout, it will work for everyone using
sublime text out of the box.