Carousel: Switch slide when pressing back/forward buttons

Before this change, the browser's back and forward
buttons would update the URL with the ID of the
desired slide, but the UI would not actually
update.

The problem was that the `open` method was getting
called for `onhashchange` events, but it would do
nothing if the carousel was already activated.
This patch adds a new method that will switch the
slide even if the carousel is already open.
Tiled Gallery: Don't wait for all images to load.

No need to wait for all images to load since we know their dimensions to begin with.
Tiled Gallery: JS object represents one gallery.

Refactored the Tiled Gallery prototype to represent a single tiled gallery as the name implies, and added a separate prototype to represent a collection of tiled galleries. This way it's clear which operations are done for individual galleries and which are done for all.
Tiled Gallery: Less responsibility for resize.

Extracted original-width and original-height attribute setting out of the resize function, and moved the call from resize to the constructor, since there is no need to see if the attributes are set in every resize call.
Tiled Gallery: Refactoring maybeSetSizeAttributes.

Made small changes to refactor the logic in maybeSetAttributes, since it was unnecessarily verbose.
Tiled Gallery: Fix square layout remainder margin.

Remainder would be short in width from the regular rows by exactly the margin. This is now fixed by not substracting the margin from the remainder size.
Tiled Gallery: Bottom margin fix.

The root cause of why the bottom/top margin between rows in Tiled Galleries is twice as wide as between columns turned out to be specific to the mosaic layout, where the rows actually had a concrete 2px bottom margin. If we remove this margin, we have a clean equal margin everywhere.
Add jetpack_log_entry action.

This will let other plugins like Stream easily log what we’re logging
as well.
Bunch of minor JP admin css tweaks

- Fixed left aligned image bug in modals at mobile resolution.
- Decreased excess padding/margin around clouds at mobile resolution.
- Show activate/deactivate links in mobile view, works on hover in
desktop
- Fixed margin-top on filter button in mobile view
- Fixed white horizontal line when left nav menu is collapsed
- Changed message on homepage to no longer mention, “Once you’ve
connected Jetpack…” if you’re already connected.
Merge pull request #502 from Automattic/ui-tweaks-dave

Bunch of minor JP admin css tweaks
AtD: Language wasn't being set, use interface language to decide with AtD language to use.
See: http://[private link]#comment-4617

Merges r96568-wpcom.
Fix HTML entity in AtD menu title

Merges r96521-wpcom.
Merge commit '36d6610'

Conflicts:
	modules/after-the-deadline/atd.core.js
REST API
Edit Posts

We shouldn't default to 'post' if no type is passed. In editing, if something is omitted it means we want it to stay the same.
(bug introduced in [96553]). This was breaking things like the DMCA tool.

Also adds a test to make sure the type stays the same (so the bug can't regress).

Merges r96732-wpcom.
REST API

Support setting and getting the per post flags for likes, sharing buttons, and G+
See http://[private link]

Merges r96757-wpcom.
REST API

Add the ability to set the sticky status of a post.
http://[private link]

props @codebykat

Merges r96759-wpcom.
Google+ Authorship

Add an option to still enable G+ but hide from display (still adds link attribute to header, etc).

See https://[private link] requested by matt.

Merges r96140-wpcom.
Merge commit '1a4196f'

Conflicts:
	modules/gplus-authorship/admin/ui.php
REST API: add new query paramater for filtering the fields returned

This query paramater allows you to specify which fields to return with endpoint responses by passing an additional comma-separated list of fields as part of the query.

For endpoints that contain one of the following objects: categories, comments, connections, domains, groups, likes, media, notes, posts, services, sites, suggestions, tags, themes, topics, users -- it will filter the contents of that object rather than the "parent" object. Otherwise, it filters the main returned object.

Comes with tests to make sure the filtering works correctly. Also removes an extra debug that was left in one of the tests.

see https://[private link] for project details

Merges r96761-wpcom.
REST API
Likes

Just check the setting directly. Jetpack_Likes will fatal on JP blogs if we don't load a file. Instead of loading a whole file just for this line, check the option.

Merges r96763-wpcom.