Update tests accordingly.  This isn't backwards compatible, but
existing clients don't rely on it.

Now we build Cython modules only if cython >= 0.16 is present.
Tarballs made by "make sdist" include the Cython-generated *.c files,
and so Cython isn't required on the end user machine at all.

At install time, the script "/usr/bin/nilmtool" will be created.

datetime_tz isn't readily available, so it's a lot easier to just
package it within the nilmdb tree.

Adjusted setup.cfg so "python setup.py nosetests" now works correctly.
Also added a "test" alias so that "python setup.py test" works.

git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@9272 ddd99763-3ecb-0310-9145-efcb8ce7c51f

git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@9269 ddd99763-3ecb-0310-9145-efcb8ce7c51f

git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@9267 ddd99763-3ecb-0310-9145-efcb8ce7c51f