WarningSink Rate Limited Logging

[vjkoskela]

Use the SLF4J logger wrapper from Commons to rate limit the warnings emitted by the WarningSink. Also evaluate if there are any other parts of the code (e.g. Metrics) which may emit log messages very frequently and use the rate limited logger by default. We may need to consider allow the rate limited logger to be configured (but it should likely be on by default).