Enable developer features in Docker containers

[jeremyprime]

Is your feature request related to a problem? Please describe.

There are a few developer tools/features that could be enabled to allow easier use of the Docker containers. For example, currently the client container does not export the necessary env vars to use Spark out-of-the-box.

Describe the solution you'd like

• Update client container environment to allow for Spark shell usage (see commands under examples/pyspark/run-python-example.sh)
• Update vertica container to start the Vertica agent (/opt/vertica/agent/agent.sh &) and map port 5444
• Update hdfs container to use a more recent image with a newer JDK, and install parquet tools (does not work on the current JDK 1.7)

Describe alternatives you've considered

Alternatively, we could just document the process, but better to just enable these useful features.

Additional context