Switch npm test to using mocha directly

[bz2]

Remove gulp-mocha-phantomjs dependency and run tests without a browser context. Loading test.html in a browser still succeeds.

Remove gulp test task.

Update to latest chai version now phantomjs is not involved.

Introduce setup file for tests that requires the needed components and populates the global object. This can be folded back into the test file later and a browser importable version generated as a step in the build process.

Only handle requests in the mock XMLHttpRequest implementation which match the endpoint url.

Resolves (half of) #51 along with #55 change to linter.

[steren]

Thanks. LGTM, but can you resolve conflicts from #55?

[bz2]

Have rebased to resolve conflicts, and added lint overrides. Trying to do reviewable pieces so there's a little juggling around required.