WIP #8 - creating an NHibernate wrapper to simplify mocking queries
Resolve #8 - add new 'get' and 'load' methods to the NHibernate wrapper

These new get and load methods serve as wrappers for the get/load methods of
an NHibernate ISession, but are strongly typed to generic IIdentity instances.

This means that these methods can return an entity of the correct type
immediately rather than needing to re-specify the type in the generic
method signature.
Merge branch 'feature/nhibernate-wrapper'