[cordova|misc|stability|webapi|wrt] Update testharness to latest

- Update testharness to latest version
  https://github.com/w3c/testharness.js (commit 2486f01bf4c58de1c1b7cb39322af7b55c6c700b)
- Add copy.py
Merge pull request #1366 from haoxli/update-testharness

[cordova|misc|stability|webapi|wrt] Update testharness to latest