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
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.
Comment out mention of Upcoming Events Widget until it actually ships
Add Tiled Gallery requirement to Gallery Widget help text
Stats: hide the Stats smiley by default
Enable i18n for 'View full site' link in Mobile theme
prevent error in post_login_form_to_signed_url

In some instances, when the `$parsed_url` doesn't have a `query`, the `post_login_form_to_signed_url()` function would emit a php notice and thus return an invalid result, which would then fail the signature checking process and thus the authentication flow would fail.

This prevents the "Someone may be trying to trick you..." notice to appear in the wrong context.

Discovered this bug while helping one of our API users debug an issue (see https://github.com/snarfed/bridgy/issues/161#issuecomment-45287830)
concat $url instead of overwriting it

props @justinshreve
Merge pull request #671 from jkudish/master

prevent error in post_login_form_to_signed_url
Removed jsbeautify

It was causing spacing issues rather than solving them.
Contact Forms: Add `process_submission` tests

`Grunion_Contact_Form::process_submission` tests, seeing that correct stuff hits
the database after processing contact form submissions and that correct email
is sent.
Contact Forms: Add `grunion_delete_old_spam` test.

Testing deleting old spam with a generated spam feedback.
Contact Forms: Improved comments in tests.
Contact Forms: More whitespace in tests.