LAM-33 Added example entries in hosts file. Created master-node file in host_vars.

ansible/host_vars/master-node.yml

+---
+# Uncomment the following line and fill the IP address of the master node.
+# master_node_ip:
+
+## Apache Flink variables.
+jobmanager_heap_mb: 256
+taskmanager_heap_mb: 512
+taskmanager_numberOfTaskSlots: 2
+parallelization_degree_default: 2
+number_of_taskmanagers: 2
+ram_per_task_manager: 768
+

ansible/hosts

 [master]
+master-node
 
 [slaves]
+slave-1
+slave-2