Fix all runtime exceptions in the browser test suite

Even with this change, browser based tests will still fail as buster's
window.when is replaced by when's window.when. As when 2 is not
backwards compatible, buster hangs.
Create a '*-test.js' matcher pattern to indicate test cases

Other *.js files should not be considered test cases.
Remove test/isPromise from .jshintignore

The warning are disabled inside the file.
Convert to UMD modules

- removed browser global support, modules all the way down
- restored browser based buster tests

Browser based buster tests will fail until
https://github.com/busterjs/buster/pull/348 is resolved and released.
With the proposed patch applied the browser tests run as expected.
Merge pull request #127 from scothis/browser-tests

Convert to AMD/Node-only UMD modules, remove browser globals, update unit tests for testing via AMD+buster+browser