Refactoring kafka::server and adding kafka::mirror support.

Recent builds of the 0.8 package do not include client configs
or commands that use client configs by default.  This makes it
mostly useless to try to configure consumer and producer property files
for Kafka client setup.  Installing the kafka package is enough,
as the /usr/sbin/kafka client commands take in a full list of
CLI opts, rather than relying on property files.

More likely, you are puppetizing a Kafka Broker.  kafka::server
has been slightly refactored with some of the required parameters
that were previously on the base kafka class.

Kafka MirrorMaker daemons can now be puppetized.  Use the kafka::mirror
class in conjunction with one or more kafka::mirror::consumer defines.
See README.md for more info.

Change-Id: Ic3d1eb24ca645e582c0d836e0a03c12541072ba8