Use built in phoenix token auth

[jeregrine]

Recently we worked to add Token Generation and Verification to phoenix, it might be nice to reduce dependencies and use the built in version.

EXAMPLE USAGE:
https://github.com/phoenixframework/phoenix/blob/master/installer/templates/static/brunch/socket.js#L10-L52

Code:
https://github.com/phoenixframework/phoenix/blob/master/lib/phoenix/token.ex

[manukall]

i think that's definitely what we should do. thanks for the links!