Support for Human Task Spring Transactions in RuntimeManager

As discussed in https://community.jboss.org/message/837019#837019 the local TaskServiceFactory used by the RuntimeManager doesn't support integration with Spring transaction management as of yet.
My guess is that the easiest way to integrate this would be a transaction manager init similar to SingleSessionCommandService#initTransactionManager(Environment env) and the use of HumanTaskSpringTransactionManager if a SpringTransactionManager is detected.

This feature would really ease the integration of droolsjbpm into spring applications and especially RESOURCE_LOCAL environments