Intermittent failure: ServiceProxyTest.testConnectionTimeout

[tsegismont]

Fixes #53

1. If "start" is created when the response to the last message is received, we can see a duration smaller than 2 seconds
2. If we use "currentTimeMillis" we can see a duration smaller than 2 seconds because of the resolution
3. Comparing nano seconds and using a non strict greater than operator is more robust

I could reproduce with @Repeat and the problem is solved with this fix.