BT 51: Fix memory leak in connector4java

Tests of a customer application exposed a memory leak in the OSIAM server that was easily reproduceable using the OSIAM stress test. The cause was jersey leaking cloned instances of internal state objects on each request as soon as the state is changed from outside the jersey client - see the existing bug: https://java.net/jira/browse/JERSEY-2378

The simple workaround was to register the HttpAuthenticationFeature on the jersey client directly instead of the WebTarget. This keeps jersey from cloning the state on each request.