Make Spark web UI accessible to S2I image port :4040

[dfeddema]

Every SparkContext launches a web UI, by default on port 4040 please expose this port to S2I generated images in oshinko.

this will give the s2i template user access to

• a list of scheduler stages and tasks
• a summary of RDD sizes and memory usage (useful for tuning and debugging)
• environment settings
• view of running executors and state of each thread

[dfeddema]

moved issue to https://github.com/radanalyticsio/oshinko-s2i/issues