Implement hoodie-server-account REST APIs

[gr2m]

Implement a generic hapi plugin with a front-end account API, backed by CouchDB. Once finished, this will be the base for the new hoodie-plugin-account core module.

Follow progress at https://github.com/hoodiehq/hoodie-server-account

• [x] session (sign in, check session, sign out)
• [x] account (sign up, get / update / destroy account)
• [x] profile (get / update profile)
• [x] requests (password resets), https://github.com/hoodiehq/hoodie-server-account/issues/30
• [x] accounts (admin only: manage accounts), https://github.com/hoodiehq/hoodie-client-account/issues/7