Don't test tools on JDK6, Scala 2.11.x (closes #1235)

They lead to spurious failures. See ticket for details.
Upgrade default Scala version to 2.11.2
Upgrade partest to 1.0.1
Partially Upgrade to Scala 2.11.4 (closes #1204)
Merge pull request #1215 from gzm0/scala-2.11.4

Upgrade to Scala 2.11.4
Refactor JSEnv to support async running