services/misc/bepasty: init at 2015-10-21

This module implements a way to start one or more bepasty servers.
It supports configuring the listen address of gunicorn and how bepasty
behaves internally.

Configuring multiple bepasty servers provides a way to serve pastes externally
without authentication and provide creating,listing,deleting pastes interally.
nginx can be used to provide access via hostname + listen address.

`configuration.nix`:

    services.bepasty = {
      enable = true;
      servers = {

        internal = {
          defaultPermissions = "admin,list,create,read,delete";
          secretKey = "secret";
          bind = "127.0.0.1:8000";
        };

        external = {
          defaultPermissions = "read";
          bind = "127.0.0.1:8001";
          secretKey = "another-secret";
        };
      };
    };