numpy installed by pip fix includes

also remove old comments
and fix numpy includes for swig! (might fix some errors we had)
numpy: update to the latest stable version

from 1.6.2 -> 1.7.1
release notes http://sourceforge.net/projects/numpy/files/NumPy/1.7.0/

Conflicts:
	external/common/requirements.txt
add source tarball for numpy to pip cache
remove numpy license, it's a dependency now
hack for matplotlib's pip install problems - numpy dep

workaround for matplotlib and asteval install bug: - numpy must already be installed
see http://stackoverflow.com/questions/11797688/matplotlib-requirements-with-pip-install-in-virtualenv
https://github.com/matplotlib/matplotlib/wiki/MEP11

numpy must be already installed, and requirements.txt file does not work, so do it manually
in build.sh before calling requirements.txt file

Conflicts:
	build.sh
	external/common/requirements.txt
Merge branch 'modular-numpy' of https://github.com/breznak/nupic into modular-numpy

Conflicts:
	build.sh
	build_system/unix/Includes.am