ServiceTracker should not use System.currentTimeMillis() to check timeouts

ServiceTracker uses System.currentTimeMillis() to check timeouts in waitForService().

If the system time changes either:

• the timeout might occur to soon - if the time was set to the future
• the timeout might not occur in a reasonable time - if the time was set to the past

Instead of System.currentTimeMillis() the system tick based System.nanoTime() should be used as it does not to change after the system time is changed.