Add a Rake task for running integration tests
Switch out all these ifdef TRACE statements for a cleaner TRACER() macro
Hold onto the Hermann::Lib::Producer pointer inside of the rd_kafka_conf_t
Add Hermann::Timeout abstraction for 1.8/1.9 compatible timeout support
Make use of Hermann::Timeout when ticking the Producers reactor to safely block for a value

This adds a requirement for 1.8.7 clients to install the SystemTimer gem for
timing out on Hermann::Result#value(timeout) to block and timeout correctly

Fixes #25