Hashed password storage

Now requires 'digest/md5'
Instead of storing the password in plaintext, it first hashes the
password using md5.
When logging in, the password is first hashed before comparing it with
the hashed stored password.
Updated md5 dependencies

Added digest/md5 to the dependencies
Merge branch 'master' of https://github.com/davenportw15/SinatraStore