Factor out test result validation
fix onlyStrict test
Better handling of error strings in simple reporter
Significant cleanup and simplification of runners

* Removed all streaming pieces from runner.js, now in bin\run.js
* Runners now have .run which compiles and executes the specified test
* Runner compilation is assumed to only produce a single test artifact.
  Any additional artifacts must be generated prior to telling a runner
  to run the test.
* Scenario expansion moved to scenarios.js (currently only strict
  and non-strict are the only scenarios we test)
* Runner now has a 'deps' property for source strings to append to
  the test before running it. Useful for runner-specific implementations
  of the test262 environment ($ERROR, $DONE, etc).