RabbitMQReport parser should parse rabbitmq cluster status

[yadneshk]

The parser RabbtitMQReport doesn't parse the Cluster status of node section from rabbitmqctl_report file.
This section is needed to check if the cluster is network partitioned.

insights-core/insights/parsers/rabbitmq.py

Lines 32 to 33 in 56abac2

	# For "Status of node" section's erlang block prasing only, could not cover
	# sections "Cluster status of node" & "Application environment of node".

I'll work on parsing this section.