Add and use a main method to each command

Use a main method to launch the command instead of doing this in the
if __name__ == "__main__" part directly . This method can then be used by
setuptools as an entry point, which will result in proper windows *.exe
commands, which cann be called from cmd.
Adapt setup.py to entry points

Use setuptools "entry_points" instead of "scripts" to get proper windows
*.exe files.
Remove old script files

The old script fieles are replaced by setuptools entry_point useage.
Add Noah Hoffman to AUTHORS.
Fix broken csvlook test.
Upgrade to dbf==0.94.
Fix for bug in latest dbf module. Pypy passes now.
Use lazy file handling to support unlimited open files. Closes #178.
Merge branch 'master' of git://github.com/onyxfish/csvkit into windows-scripts

Conflicts:
	csvkit/utilities/csvstack.py
Add Jan Schulz to AUTHORS.
Add note about Python version compatability.
Update to latest version of dbf module.
Merge --not-columns support. Closes #162.
Implement csvpy. Closes #44.
Clean up ugly comments.
Handle edge cases in csvpy.
Update CHANGELOG.
Add note about platform support.
Optimize 8bit encoding as suggested by @gpoulter. Closes #175.
Clean up stdin handling in csvpy. Closes #179.