v0.0.22 - Basic Geni CLI + Namespace Alignments

Better getting-started experience with the new geni command and better alignment of Geni namespaces with Spark packages.

• New geni script with install instructions and a new asciinema screencast. This will be the main way to use Geni for small, one-off analyses and throwaway scripts.
• Created another layer of namespaces with zero-one.geni.core and zero-one.geni.ml. The idea is that the core namespaces should refer to only Spark SQL and the ml namespaces refer to Spark ML. This will help the mapping of Geni functions to the original Spark functions.
• Added a simple benchmark piece that compares the performance of Pandas vs. Geni on a particular problem.
• An asciinema screencast for the downloading the uberjar and interacting with the Geni REPL.