Shared: Refactor out Navigators and Renderers.

The poorly-named Client and Renderer were each performing two jobs:
rendering React components and navigation via the configured Router.
This commit breaks those jobs into two new classes, removing the old
classes altogether.
Context: Move to this.context.

React has a not-yet-documented 'context' feature that allows this
convenience. The use of this feature is contained in Container and
Mixin, shielding users from the added entropy.
Client: Remove extraneous console.log.
Mixin: Allow without mappings.
Server: Fix rendering head elements.
Context: Add programmatic navigation.

Side effect: The Router is no longer available directly from nor
added as a configuration option to Navigators. As a result, Routes
should be added using the Context API much like Actions and Stores.
Container: Clean-up and add docstrings.

In addition, the Mixin's contextTypes are now automatically kept in
lock-step with the Container.
Test: Add Router tests.
Test: Add Context tests.
Test: Explicitly order tests.
Test: Add StaticRenderer tests.
Test: Use cheerio for HTML assertions.
Test: Add Container and Mixin tests.
Router: Add extra params as query in getRouteUrl.
0.10.0