#416 - Unable to deploy rar JDBC with the embedded driver

[backport from trunk]

* Rar.processRar() was called within an IExecution block setting the resource
  service Bundle's ClassLoader as TCCL
* Within the execution stack, ManagedConnectionFactoryImpl.getDataSource()
  was using the TCCL to load the DataSource implementation class
* Changed this to use as TCCL the ClassLoader that contains RAR resources