Export archive to unique file name

Currently, the archive is written to a file in the export directory with the same name as the archive. However, many of the test archives are named "test.war". So when a suite is run, the only exported archive that remains is the last one exported.

Instead, the file should be prefixed with the full qualified test class name, which is customary for other files such as surefile results.

For example, if the test is com.acme.SampleTest and the archive is named test.war, the following file would be created in the export directory:

com.acme.SampleTest.test.war