Better password security

[iodbh]

Password security as it is is not suitable for production use :

• We are using sha256, which is too fast for password hashing (see this)
• The hashes are unsalted, which make cracking a breeze

I would recommend switching back to passlib, which implements recommended algorithms and conveniently wraps hashing.

[ghost]

I think we should use the werkzeug module that comes with Flask, utils have some usefull functions. passlib doesn't seem to be maintained anymore.

[bhark]

There's also bcrypt, which looks like a solid choice. Allows us to dictate slowness and salt easily. It seems like it's being worked on still. On GitHub here.

[bhark]

I finally got a new laptop, so if you're both alright with using bcrypt, I'll implement it instead of hashlib.

@iodbh @surrealbytes

[bhark]

We're now using bcrypt.