remove btm related classes from jbpm-shared-services

split jbpm-shared-services into two jars - default one without any bitronix dependencies and second one (with btm classifier) that includes these classes. THe btm one shall be used for hosted mode and non app server - like tomcat jetty etc where JTA transaction manager is bitronix.

What do you think about this? Does it make sense to keep it that way?