Fix #1060: Cleanup scala.scalajs.test namespace

Its elements are moved to different namespaces as follows:

Scala.js Test Suite    => scala.scalajs.testsuite
Test Bridge            => scala.scalajs.testbridge
Jasmine Test Framework => org.scalajs.jasminetest

Also, the RhinoJSEnv is updated to undefine LiveConnect classes after
including env.rhino.js. No research on why this helps has been
performed (but it does help).
Merge pull request #1085 from gzm0/cleanup-test-namespace

Fix #1060: Cleanup scala.scalajs.test namespace