Merge pull request #16 from mdboom/faster-http-testing

Use multiprocessing rather than threading for "test" webservers
Use wheels for numpy and cython.
Merge pull request #17 from mdboom/travis-wheels

Use wheels for numpy and cython.
Improve how "explode" works -- allow for deep linking to blocks inside
of FINF files.
Add a test
Allow referencing of blocks within FINF files.  Greatly increase code coverage.
Python 3 fixes.