Add CI tests over a remote Spark cluster

[imarios]

• Bring a very basic cluster up and then deploy a toy Frameless project packaged using sbt-assembly
• Read data back/forth from Paraquet
• Read data back/forth from CSV and JSON

[tscholak]

maybe as a first step it should be investigated if there is a way to run the tests in cluster mode on travis.

[tscholak]

here is something useful: https://github.com/holdenk/spark-testing-base/blob/master/.travis.yml