Investigate if there is a way to install Hail 0.2 via a user script

[rtitle]

Leo uses Dataproc 1.1, Spark 2.0.2, and Hail 0.1. We'd like to support Dataproc 1.2, Spark 2.2.0, and Hail 0.2. That work is tracked in the below tickets.

#193
#144

HOWEVER, it may be possible to run Hail 0.2 on a Spark 2.0.2 cluster. This ticket is to see if we can create a user script that allows usage of Hail 0.2, but without other changes to the Leo/Spark environment (in other words, allows using Hail 0.2 on Leo clusters as they exist today).

[rtitle]

Decision: since there is no urgent user need for this, we will instead devote our time on full support for:

• Python 3.5
• Spark 2.3.0 (?)
• Hail 0.2
• Pandas recent

since these are all interrelated. See #488 for context around upgrading pandas.