Write implementation example for upgrading user passwords to password_hash

[jeremykendall]

See discussion in #7.

what would people learn that they wouldn't learn from what I already wrote?

I'm a big fan of examples of practical application. I see a big opportunity for code examples that would flesh out the information in the blog post.

Maybe just seeing a complete example, using Password Validator?

That and an example of what the DB update might look like. Devs who haven't implemented safe password hashing and storage may not (would likely not?) have the skill set to plan out the db update and migration.

If you want to make up a first draft sample, I'd be happy to work on it, though.

Will do.