Add units tests to Ansible roles

[jasonrhaas]

After running an Ansible role, we should run a small test to ensure that the tools are actually working properly. Some examples:

• Elasticsearch - index a small document
• Hbase - write a new table row
• Hadoop - create a file, run a map reduce job
• Spark - run a wordcount
• Kafka - produce some data to a topic

In the .travis.yml we could just add another line to the script: section that runs some python or Ansible code after it finishes provisioning the role.

[madisonb]

• Docker - run the Docker Whalesay hello world
• Apache - hit the Httpd server to get the index page response
• Redis - set and get key
• Tor - initial a connection to a stable onion address
• Zookeeper - write a new file