Lint jmxfetch and sort the list of JMX checks.
Add a kafka check, pulling metrics from JMX.
Use single quotes in kafka YAML to make it more readable
Fix kafka metric types and names.
add check to track kafka consumer metrics
only show a stack trace for unexpected zk read errors
report the broker offsets separately from the consumer offsets in case there are partitions without consumers
[kafka_consumer] raise exception if using python < 2.6
use backported defaultdict implementaion, to stay consistent with the rest of our code
provide better feedback on config errors
raise a more descriptive error when missing dependencies
check for both missing yaml keys and keys with no value
Update Kafka check from code review.
Merge branch 'master' into kafka-check

Conflicts:
	jmxfetch.py
Remove kafka from list of JMX checks.
Merge pull request #810 from DataDog/kafka-check

Kafka check - first pass