Configure and install required services

This pull request is a part of the issue : https://github.com/DemandCube/hadoop-single-node-cluster/issues/9

Usage:
-s - Prints all the services
-a "SERVICE1 SERVICE2"  --> forces by default and installs the services mentioned
This works when the cluster is already running.  When running this to install a new cluster from scratch this doesn't work.  You should need to change the published file (blueprint-raw.json) so that the fresh install will only install the selected components.   Alternatively maybe a good difference is to have a minimal install that only installs HDFS and the rest of the components can be added with a second call to this script.

What do you think?