Updating the contribute URL to https://github.com/mozilla/browserid/blob/

Updating the contribute URL to https://github.com/mozilla/browserid/blob/master/browserid/static/users.html

update tutorial now that the verifier returns the unpacked assertion, and address thunder's concern about providing sample code for the server in client side javascript.  closes #32

if you can verify an email, you can take ownership of it.  this should trigger some fun conversations with thunder. closes #36

move to bcrypt for password hashing and storage.  This satisfies @benadida's crazy paranoia, so it closes #35.  In other news, the 'forgot password' flow is now complete (this change solves the case where you forget your password for an email and reset it with precisely the same password --- because auth is salted, the registration_status call will delay 'complete' until you actually click through.  tl;dr; - closes #18

fix registration_status - now it's more sophisticated.  in case you're adding an email it needs you to be authenticated and checks that the same user owns both emails addresses.  in case you're verifying or re-verifying an email to creat an account it checks to see if the new credentials you provided work yet (transition only occurs when you click through the email link.  all tests passing again.