ISPN-3097 Improve total order test suite

* bugfix: if the PrepareCommand and CommitCommand are delivered at the same time, the RollbackCommand was triggered in TxInterceptor.

https://issues.jboss.org/browse/ISPN-3097
updated:
and also https://issues.jboss.org/browse/ISPN-3146

changes:
 * bugfix as described above
 * the simple test cases extend a common base test implementation
 * added more tests varying the configuration
 * before each assertion, the test waits until all the nodes involved in the transaction sees commit it.