version is now set from git describe
version checking uses absolute file paths
fix bug in version.py subprocess call
documentation version uses version.py
fix easy_install instructions in INSTALL.md

easy_install cobra not cobrapy
Use manually updated RELEASE-VERSION
setup calls new version function
VERSION is a better name for the file
version.py hunts for git.exe on Windows

On windows, it is possible that git will not be in the path but the code
will still be in a git repository. A good example of when this may
happen is using the github application.
Merge pull request #12 from aebrahim/version_release

Use a VERSION file and git describe