JSON API: Allow Public CPTs by default.

Up until now we have allowed pages and posts to be accessed via the JSON
API with a whitelist filter that can be used to add CPTs to the allowed
list. This has 2 problems:

1.  The API does not get all public posts out of the box needing developers
    to add both the CPT and a filter to allow public CPTs to show up.
2.  When specifying type 'any' only posts and pages are returned even after
    CPTs are whitelisted making it impossible to get posts and CPTs
    together in one call.

This patch adds a new blacklist filter so that all public CPTs are
avaliable by default (with the abality to turn them off for the API) and
allows the 'any' special type to return all post types allowed.
Add global JP filter for allowed post_types
Use protocol-relative URL for Google Web Fonts.
Configuration menus: change breadcrumb link to settings page

Fixes #611
Configuration menus: use Jetpack::admin_url() instead of menu_page_url

See https://github.com/Automattic/jetpack/pull/616#issuecomment-44701300
Trigger change event when clearing module search

This ensures that the modules get re-filtered when the user clicks the little (x) in the module search box to clear their search.

fixes #613
JSON API authorization: Fix error comparing signatures when the WordPress installation is using site_url filters.
Changes/additions to gruntfile.js

Did my best to get pretty close to WP CSS code standards, but haven’t
figured out how to retain newlines… Yet.

Autoprefixer has been added.

You will need to run `npm install` again. Grunt watch is now 100%
beefier.
Updated sass paths.
Mobile Theme: Fix spacing for comment reply heading
Mobile Theme: Close head element
Merge pull request #638 from kraftbj/mobile-theme-head

Mobile Theme: Close head element
Comment out mention of Upcoming Events Widget until it actually ships
Add Tiled Gallery requirement to Gallery Widget help text
Merge pull request #637 from kraftbj/mobile-theme-reply-fix

Mobile Theme: Fix spacing for comment reply heading
If we're inserting dynamic input, use .text()

Things can get funky if the search string includes html.
grunion: apply jshint

Merges r98447-wpcom.
REST API: add default sharing, likes, comment and ping status to the `options` response part of the `sites` endpoint

Merges r98437-wpcom.
jshint: Unignore grunion.js
Merge pull request #645 from Automattic/wpengine-oauth-error

JSON API authorization: Fix error comparing signatures when the WordPres...