RemoteSchedulerTest can fail depending on performance/timing

I'm currently trying to get building Zeppelin's 0.5.0 stable, and stumbled across another intermittent failure:
RemoteSchedulerTest.java$L121''s assertion failed randomly, I presume because the 500ms thread sleep before was insufficient. I will provide a patch adding another 500ms should the first comparison fail, before asserting, in order to have a quick build in the normal case, with minimal waiting, and a slower build, should there b a performance issue. While not a perfect solution, this is probably the best hope to avoid broken builds for no reason with a higher probability.
I'm assuming that this error is also present in master, at least the relevant source code is identical.