Upgrade to python3 & implement requirements.txt

[Script-Nomad]

I needed this for a penetration test and in its current implementation does not work. In fact, it broke my python2 installation because enum package is not supported by python2.7 anymore, and has been deprecated. I did some extensive work to futurize this because well... yeah I needed it.

So, quick summary of what I did.

1. Futurized all packages to python3
2. Moved up packages to latest implementation
3. Implemented requirements.txt according to the pypi documentation
4. Refactored all py2 code to python3
5. Excised the cancer that is enum in place of the now supported enum34

This code is largely untested, although I was able to run several commands successfully and generate a valid (forged) SAML Response out of it. Please test and update this code for the sake of your users. It's an awesome tool. Cheers :clinking_glasses: