several minor fixes

bin/run.js:
- expect flags without = to be boolean
- prevents --testStrict from eating first filename

lib/helpers.js:
- use test/harness as helper dir if present

check for existence of test/harness (running in test262 dir)
if present, use test/harness helpers instead of those in
test262-harness lib dir

lib/parser.js:
- recover from and log yaml parse errors

lib/runner.js:
- shorten pass/fail logic

lib/simpleReporter.js:
- only write errorMessage if present