Fixed broken links to w3c-test.org (specs and test suites)

A number of specifications and test suites got moved to different folders on `w3c-test.org`. This commit should fix all broken links that appear in the final roadmap.

As an exception to the rule, I could not find the tests referenced by the `inputaccept.json` file for the Media Capture specification. I see there's an on-going pull request at:
  `https://github.com/w3c/web-platform-tests/pull/306`
... but files do not appear under `http://w3c-test.org/submissions`. The broken link remains.

Not related but note the notifications API tutorial is no longer available on `WebPlatform.org` so I dropped the section from the `notification.json` file.