Added kafka_install method

Added a new method and install type for Kafka installation. kafka installation requires Zookeeper to be setup and running before Kafka server can be installed/configured. The new method first installs the Zookeeper nodes and then moves on to installing Kafka Server nodes.
Please use the exact role name (i.e. BCPC-Kafka-Head-Zookeeper) here and lines 205, 209, 213 (and on 216 for the Kafka role).

Perhaps factoring these two role names out into a variable would make the role more obvious and easier to change should we need.