ubuntu 18.04 Hadoop, Spark, sparklyr installation

Despite instructions, I spent some time on this because of Java compatibility issues.

1. following instructions here, install oracle java 8.  Do the update-alternatives thing and make sure java 8 is your default.
2. following instructions here install hadoop.
3. follow these instructions to install spark
4. in R, install.packages("sparklyr")
5. you should be able to fire up the sparklyr tutorial at this point.