Appending additional string data to a reraised exception is too prone
to breaking if the 'args' attribute does not faithfully record the
__init__ arguments of an exception, which is apparently all too common.

No longer need requirements-*.txt as requirements can ALL be listed in
setup.py with setuptools. Also py-unittest-extra can be downloaded by
setuptools so no longer needs to be a submodule.

Also added setup.py metadata, and a couple extra patterns in
.gitignore.

Hopefully should fix a bug of some sort in python < 2.7.9

Started with:
 * set of three utility modules
 * unittests for each of the above
 * setuptools based setup.py script