Also set up environment-related details needed for a smooth Cython
experience: have the test script avoid rebuilding all dependencies if the
virtualenv directory already exists, have the PyPI distribution script
distribute the Cython generated C code rather than the .pyx files.
Update LICENSE text to 2015, implement a checker that validates
whether a 2014 or 2015 version of the license is on each {.c,.cc,.h} file.
Fix the ones that are missing it.
Masood Malekghassemi
Craig Tiller
Nicolas "Pixel" Noble
Yang Gao
Craig Tiller