Update have_configured matcher

* Use Regexp.quote for @value as well.
* Explicitly create a RenderFileMatcher.
* Better failure message.
* Force @value to a String.
Set KAFKA_GC_LOG_OPTS in environment file
Add integration tests as well
Merge pull request #11 from mthssdrbrg/override-kafka-gc-log-opts

Override default log path for kafka GC logs

Fixes #7.