Remove tox.ini.

Tox has been unstable at best since various changes in virtualenv and
pip so I've abandoned its usage for the time being.  My public builds
run through Travis CI so I get the 2.7 + 3.3 coverage there.
README: Add development environment section.
Makefile: Add a basic makefile.
Makefile: Add housekeeping targets.
Makefile: Add test target.
Makefile: Add lint target.
Makefile: Add sdist target.
Makefile: Add docs target.
README: Fix formatting error.
Merge branch 'feature/rework-build-environment' into develop
Add __version__ attribute to fluenttest.

The __version__ attribute is the public version identifier and is
server safe.  The version_info tuple contains the full version.
Replace hard-coded version with __version__.
Fix clean targets in Makefile.

`find ... -delete` does not seem to work when the target directories
contain children so I reordered the __pycache__ cleanup stuff in the
Makefile.  It *should* work now.
Merge branch 'feature/semanticize-versioning' into develop
fluenttest.TestCase: Add destroy method.
docs: Add change log.
Merge branch 'feature/add-destroy-hook' into develop
docs: Remove mention of patching magic.
test_case_tests: Remove usage of NamedTuple.
fluenttest.TestCase: Remove patches attribute.