Features/with sopt

@jenshnielsen,

Provides compilation on:

- Mac + (homebrew or canopy) python + (clang or gcc)
- ubuntu
- legion + (gcc/atlas or intel/mkl)

Main new build features:
- mechanism to pull missing libraries from the web, namely CFitsIO and sopt
- mechanism to create scripts with (DY)LD_LIBRARY_PATH set correctly, such that test scripts can be run from the build tree, and still find the purify library
- mechanism to check for the existence of python packages on the system
- mechanism to create a virtual environment in which to run the python tests. This virtual environment will find the purify package in the build tree

Most of this is implemented in the [cookoff](https://github.com/UCL/GreatCMakeCookOff).
Finally on our jenkins server.