Upgrades ScalaTest assertions

[cdupuis]

---
kind: "operation"
client: "rug-cli 0.23.0-SNAPSHOT"
executor:
  name: "UpgradeScalaTestAssertions"
  group: "atomist-rugs"
  artifact: "scala-editors"
  version: "0.1.0"
  origin:
    repo: "n/a"
    branch: "n/a"
    sha: "n/a"

[CLAassistant]

All committers have signed the CLA.

[cdupuis]

@johnsonr added you as reviewer to let you decide whether or not you want to merge this in.

[kipz]

Love it! +1

[claymccoy]

This is great.
One thought, DiagrammedAssertions given even better messages on failure and don't require the triple equals.
http://doc.scalatest.org/2.2.1/#org.scalatest.DiagrammedAssertions