Update and simplify common requirements 

This updates the requirements to newer versions.

I also remove Jinja2, MarkupSafe, Werkzeug, argparse, itsdangerous, wsgiref, paramiko, pycrypto, ecdsa, SQLAlchemy because they were installed as dependencies. I think it will simplify things for someone who wants to update the requirements in the future.

* Jinja2, MarkupSafe, Werkzeug, argparse, itsdangerous, and wsgiref were all installed with Flask
* SQLAlchemy is installed with Flask-SQLAlchemy
* paramiko, pycrypto, and ecdsa are installed with Fabric
Merge pull request #8 from pawl/patch-4

Update and simplify common requirements