[BUILD] updated ant build file

The classpath was in wrong order and so wrong classes were loaded during
runtime when executing the JUNIT tests.

Change-Id: Ie530cd82d64db89c8b130be27b15af3c64347e04
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1283
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>