Move test-runner.js to tests directory.

I also moved dom-shim-tests.js to its own directory for
better organization.
Add information about the DOM shims to the README.

I updated other API documentation to show what parameters
they take as well.
Make vtt.js node and npm friendly.
Release v0.10.1
Specify files for npm and node in package.json.
Add keywords to the package.json.
Release v0.10.2
Add vttcue.js and vttregion.js to files list in package.json.
Release v0.10.3
Use 'encodeURIComponent' instead of 'escape' as it is deprecated.
Release v0.10.4
Update node section of README.
Use node-vtt from npm instead of local.
Install bower globally on travis.

This will get around the problem that node-vtt is having
currently where npm isn't updating its 'postinstall'
script correctly.