[ospec] Improve the dupe detection code

Render false as an empty string

Avoid intermediary component constructor

Very specifically doing a strict `false` check here to try & avoid
coercion perf costs.

Remove extra code from example that is not required

Replace x instanceof Array with Array.isArray(x)

Remove o.only call to ensure other tests are run.

Recommend usage of fragments

Remove duplicated install

[ospec] deepEquals corner cases with undefined values

Recommend 'budo' for the quickest start ever

Fewer steps to get a complete app running in the browser with live reload.

Add support for `options.headers` in `m.request` + tests/docs

I also had to edit the mocks accordingly, so I could inspect the headers set.

Fix added `header` parameter + update docs, fix a few nits

Fixes #1463.

Make it work in a browser

Fix #1489: PromisePolyfill always overwrites `window.Promise`

[ospec] Speed up the CLI runner by skipping node_modules early

# Conflicts:
# api/router.js

Ensure the back button test checks the right thing.

Back button on default route