[OutputBuilder] WIP: Enable display of rule RHS data received from server.
[OutputBuilder] WIP: Enable display of rule RHS data received from
server.

1. Introduce new Backbone model for representing RHS and add an instance
   of it to the rule model instance that is constructed based on
   information received from the server.

itsjeyd/ODE,itsjeyd/ODE,itsjeyd/ODE,itsjeyd/ODE