Compile time flags can now be passed via build and install:

python setup.py build/install --define="BYTETRACE, FOO, BAR=3"

will result in the the extra compiler args:
-DBYTETRACE=1 -DFOO=1 -DBAR=3
Merge pull request #9 from pbrady/setup_define

Compile time flags can now be passed via build and install