Wrap tests and linting with tox

Use tox configuration to expose linting and unit testing. Will let us
integrate them with OpenStack continuous integration infrastructure.

* updates .gitignore following the migration from bzr
* get rid of the old Makefile in favor of tox
* remove .pep8 file (that is now a [flake8] section in tox.ini)
* fix a few trivial pep8 errors (comments must start with '# ' and
  modulo operator needs surrounding spaces) but ignore 'line too long
  (E501)' for now.
* write module requirements in /test-requirements.txt. Discover is
  needed for python 2.6.
* change the test command that cames from the Makefile so it works with
  python 2.6

Change-Id: If58730d84315c0ea018a3757624d98bf2e1aeb3f