Revisit zingg.sh

[navinrathore]

Description
"zing.conf" file should include other zingg variables as well. It should be central point for defining zingg configuration.
zingg.sh should be changed accordingly

Ref: PR #253, issue #15

[sonalgoyal]

There are a few other changes we now need in the script to run the python files. The plan is to have some new phases(assessTraining for eg) run completely through python, and existing ones through java. So, we need to parse the args, check if the phase is a python supported phase, and invoke corresponding phaseName.py file through spark-submit.

To parse the phase, please check https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash

To invoke spark-submit with python files, please check https://spark.apache.org/docs/2.4.3/submitting-applications.html. In this case, we will not be calling --main-class. We may also need to send --py-files. You can test with the example python api we have in the repo.

[sonalgoyal]

@navinrathore please check #243 (comment)

[navinrathore]

As of now, spark configuration can be read from the zingg.conf file. Through the same file, environment variables could also be defined.