Link taxonomies to their associated collections

[danielbachhuber]

Changes $data from an array to WP_REST_Response when
supplied to rest_prepare_taxonomy

Fixes #1381

[danielbachhuber]

@WP-API/amigos #reviewmerge

[danielbachhuber]

local ➜  ~  http GET http://wordpress-develop.dev/wp-json/wp/v2/taxonomies/category --body
{
    "_links": {
        "collection": [
            {
                "href": "http://wordpress-develop.dev/wp-json/wp/v2/categories"
            }
        ]
    },
    "description": "",
    "hierarchical": true,
    "labels": {
        "add_new_item": "Add New Category",
        "add_or_remove_items": null,
        "all_items": "All Categories",
        "choose_from_most_used": null,
        "edit_item": "Edit Category",
        "items_list": "Categories list",
        "items_list_navigation": "Categories list navigation",
        "menu_name": "Categories",
        "name": "Categories",
        "name_admin_bar": "category",
        "new_item_name": "New Category Name",
        "no_terms": "No categories",
        "not_found": "No categories found.",
        "parent_item": "Parent Category",
        "parent_item_colon": "Parent Category:",
        "popular_items": null,
        "search_items": "Search Categories",
        "separate_items_with_commas": null,
        "singular_name": "Category",
        "update_item": "Update Category",
        "view_item": "View Category"
    },
    "name": "Categories",
    "show_cloud": true,
    "slug": "category",
    "types": [
        "post"
    ]
}

[rmccue]

Closing parens are a level off here.

[rmccue]

Looks good apart from minor coding standard tweak.