Migrate simple classes to hibernate4 equivalents

This commit contains a handful of "simpler" updates moving from
hibernate3 support in Spring to hibernate4. Specifically:

* `HibernateCallback`, `HibernateTemplate`, and `HibernateDaoSupport`
  work mostly the same in hibernate4, so import statements were simply
  updated. Note: it is recommended to replace
  `HibernateCallback`/`HibernateTemplate` code with "plain" Hibernate
  style calls using the new `SessionFactory.getCurrentSession()` method
  introduced in Hibernate v3.0.1.
* The `allowCreate` parameter from the `HibernateTemplate` constructor
  was removed, as `HibernateTemplate` is now using `getCurrentSession()`
  under the covers.
* `SessionFactoryUtils` has been severely trimmed down in hibernate4. In
  particular, the `getSession()` method (along with the `allowCreate`
  parameter) has been removed in favor of `getCurrentSession()`.
* One instance where `HibernateInterceptor` was imported but not used
  was removed (`HibernateInterceptor` no longer exists in hibernate4).
* Import statements for a few exception classes were updated.