add brew formula for Python 2.6
test on osx
install cmake
try Python 2.7 instead
try Python 2.7 instead
try install without pulling new Python version
set PATH and PYTHONPATH and install locally
set environment variable in before_install
try local install without setting environment
call script from correct location
call tests with usual python setup.py test method
test multiple networkx versions
install pip
install networkx locally