Use workspace specific TMP directory in Maven build

Depending on build server configuration it was possible to run into
permission problems when running the tests from the Maven-build in a
standard file layout; this change is setting the location of the tmp
directory for everything executed by Java and by Maven.

Change-Id: I6cfee9fd1a7694408d0cca43d87927f4f7a6f99a
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>