Save web sessions state in a service

[pablodip]

User Story

As a devops I want to restart the web server or change it to another server without it losing web sessions state.

Description

Right now it's being used immutant.web.middleware/wrap-session to save the state.

The expected behaviour is to save the state in Postgres, so that we can just not add more kinds of services for now. It could be done with https://github.com/luminus-framework/jdbc-ring-session

The table should be created when starting the app if it doesn't exist.

Some docs about this topic: http://www.luminusweb.net/docs/sessions_cookies.md