[SW-51] Add pysparkling egg on PYTHONPATH during launching pyspark
[SW-51] Add pysparkling egg on PYTHONPATH during launching pyspark

This is workaround for yarn-client mode since even we passes `pysparkling.egg` via
`--py-files` option of pyspark, the `pysparkling` package was not available from Python shell

h2oai/sparkling-water,h2oai/sparkling-water,h2oai/sparkling-water,h2oai/sparkling-water