bump scalatest to 2.2.2

mostly to pick up wildcard test-suite handling, e.g.:

    $ mvn test -Dsuites="*MdTag*"

(hammerlab has a helper around this for even more convenience; see
https://github.com/hammerlab/internal-tools/blob/master/scripts/mvn-utils/mvn-test)
Merge branch 'scalatest-fix' into upstream-master

This is a re-merge of the (re-based) 'bump scalatest to 2.2.2' branch
into master, since I (tdanford) messed up the merge the first time.
[ADAM-360] Upgrade to Spark 1.1.0.