test separate script to run  python installs in case we dont want virtualenv
BUGFIX: pip install $requirements_filename, not requirements.txt
include non-virtualenv python include dir when looking for numpy
move requirements.txt's comments about cx_freeze into install_cx_freeze.sh
don't install cx_freeze by default
try to simplify install scripts
add git, pip to system dependencies installed
remove git as dependency
Merge branch 'virtualenv_cleanup'