Better support for custom content types

[artoliukkonen]

Currently only way to query custom content types is with .root method.

/**
 * Generate a query against an arbitrary path on the current endpoint. This is useful for
 * requesting resources at custom WP-API endpoints, such as WooCommerce's `/products`.
 *
 * @method root
 * @param {String} [relativePath] An endpoint-relative path to which to bind the request
 * @param {Boolean} [collection] Whether to return a CollectionRequest or a vanilla WPRequest
 * @return {CollectionRequest|WPRequest} A request object
 */

It'd be great to be able to define your own custom content types so one would be able to use those just like .posts and .pages . I have some ideas how to achieve this, will try to do a pull request soon.

[kadamwhite]

@artoliukkonen We're discussing options for this in #144 and related issues

[kadamwhite]

.registerRoute (#176, merged) and Auto-discovery (#74, WIP) are the resolution for this, and those issues supersede this one.