[jbpm-dev] jbpm-core --> jbpm-jpdl

FYI, while updating the docs, i noticed a serious mismatch. jbpm-jpdl had been changed with jbpm-core. To prevent confusion, I'm changing the artifactId from jbpm-core to jbpm-jpdl. I still leave the module in directory modules/core. I have build the installer and run the core test suite. Now I'll be running full test suite: first building, installing and starting jboss and then running the full test suite including the enterprise tests. When that succeeds locally, I'll check in and start a hudson build. Also, the download I renamed to jbpm-jpdl-{version}-installer.jar to be in sync with previous namings. -- regards, tom.