Add support for 2.2. to master (via shaded jars)

This patch does a few related things. NOTE: This may not compile correctly for ~24 hours until artifacts fully propagate to Maven Central.

1. Uses shaded versions of akka/protobuf. For more information on how these versions were prepared, see [1].

2. Brings the `new-yarn` project up-to-date with the changes for Akka 2.2.3.

3. Some clean-up of the build now that we don't have to switch akka groups for different YARN versions.


[1]
https://github.com/pwendell/spark-utils/tree/933a309ef85c22643e8e4b5e365652101c4e95de/shaded-protobuf