Updated packaging setup to work better.

- Fixed the wrong parameter to setup() was used for install james.py as a module (must be `py_modules` instead of `modules`)
- Conditionally install dependencies that enable SNI only on Python 2.x as it's available on 3.x.
- Add license parameter.
- Use setuptools entrypoints for console script instead of pure script to fix issues on Windows and executable bit on *nix systems.
- Stop using ez_setup.py as it's not available at all and setuptools can be assumed.
- Stop using requirements.txt as it's misused for this case.
- Fixed the manifest template to actually include the README file and remove the others because they are obsolete or automatically added to the package.