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
Removed jsbeautify

It was causing spacing issues rather than solving them.
Omnisearch: change heading color back to black

We do not need white headings now that we do not add bg clouds anymore

See kibbling/1955
Contact Forms: Subject can have replaceable tokens

Contact Form subjects can contain tokens, like {city}, where a form field with
name City (case insensitive) will be searched for, and the value of {city} is
replaced by the sanitized value of that field.
Contact Forms: Add `$all_fields` to subject filter

The `contact_form_subject` filter now receives an additional argument
`$all_fields` which is an array with the fields' label names as keys, and the
fields' values as values.

Refactored the hook for token replacing in the subject to use the passed field
value array instead of fetching the current form.
Contact Forms: Refactor subject token replacement.

`replace_tokens_with_input` replaces token values more neatly by using
`str_ireplace` with all the possible token strings and their corresponding
values.
Contact Forms: Update PHPDoc.
Contact Forms: Extract anonymous functions for bc.

Extracted anonymous functions from `replace_tokens_with_input` as static
methods for PHP backwards compatibility.
Contact Forms: Trim labels before tokenizing them.

When replacing tokens with field values, let's trim the labels of any possible
whitespace before tokenizing them for the replacement.