Fix tests on jenkins

When the tests are run on the build server, they are run from the jar,
as opposed to the extracted build, which is default when run from an
IDE. Thus, when class.getResourceAsStream() is called with ".." in the
path, it is not resolved properly. This change explicitly resolves the
relative path, so that the test is run properly on the server.

Change-Id: Ib5fabd617dca4052220e5173a8bf4fb4234254ff