launchApp jnlp should not automatically open www.jalview.org/examples/exampleFile.jar if no open parameter is given

The launchApp servlet traditionally included a default argument '-open http://www.jalview.org/examples/exampleFile.jar' as a form of debugging tool for developers, but this is no longer necessary. It also conflicts with the use of the servlet for launching jalview with different memory settings - so the inclusion of the default option should be dropped from the servlet code.