Changelog: clarify removal of G+ Profile

This should avoid confusions with Publicize
See https://wordpress.org/support/topic/jetpack-32-removed-google-module for some background on this
REST API: adjustments to CORS/preflight

* Move the action to fire before authentication is processed. Authentication shouldn't be necessery for the preflight requests.
* Explicitly output with a 200 status for preflight requests

This is an attempt to fix a production/firefox specific issue. However even if it doesn't fix the issue, these improvements still make sense as they do not cause any regressions and make the output a bit cleaner for these requests.

Merges r108139-wpcom.
REST API: Add 'slug' to plugins format.

+ Add some missing safehtml escapes.
See: https://github.com/Automattic/jetpack/commit/2b4575b882b2d7ad7218f911994bdde215e29672
Pinking shears

Merges r107783-wpcom.
REST API: /me/posts endpoint. Return the Jetpack author.

We were returning the wpcom user data instead of returning the Jetpack author data stored on post_meta for jetpack sites.

Merges r108070-wpcom.
REST API: /me/posts Endpoint: Improve readability.0

Merges r108079-wpcom.
REST API: Add sharing button settings to site settings endpoint

Includes: "sharing_button_style", "sharing_label", and "sharing_show"

Merges r107856-wpcom.
REST API: mark the embeds and shortcodes endpoints (listing and rendering shortcodes/embeds) as documented under the `sites` group

Merges r107927-wpcom.
REST API: Implement Sharing (ShareDaddy) set of endpoints

The purpose of these endpoints are to list and view sharing services (enabled and disabled, hidden and visible), and to enable the creation, updating, and deletion of custom sharing services.

Merges r108193-wpcom.
REST API: Get Site: add jetpack_version.

Merges r107782-wpcom.
REST API: add the date/time that a site was created in to the results of the sites endpoint

Also fixes the sites options test as it wasn't properly checking for the properties

Merges r108134-wpcom.
JSON API: Use `WP_Date_Query` instead of manually modifying the MySQL query for Comments List endpoint.

`WP_Comment_Query` caches based on its known arguments.  It doesn't understand when we manually edit the comments query that a different cache key should be used.

Switching to its `date_query` argument (which uses `WP_Date_Query`) ensures the cache key will always be different for different comment queries.

Additionally, move tests from old suite to new suite.
REST API Test Suite: Force "sticky" flag to match requested input on post create/edit

We've been seeing intermittent failures of 'create_post_with_sticky_should_be_sticky' and
'can_edit_post_and_change_sticky'. It appears that the post stickiness is being set
correctly, but there might be a race condition where stick_post() is not completing
before the post information is pulled to be returned. So let's just assume stick_post()
/ unstick_post() work, and echo the requested value back (forced to boolean).

Merges r107757-wpcom.
REST API: bug fix for the media v1 endpoint and improvements to the media tests

* Fix a typo in the media v1 endpoint
* Add groups for the media tests (v1 vs v1_1)
* Add tests for the delete endpoints
* Properly delete media in the v1_1 endpoints
* Add assertions for errors to make sure they are as expected

Merges r108088-wpcom.
REST API: Adds current_user_can node to post response to pass per-post capabilities

Merges r107738-wpcom.
REST API: don't check if a post is freshly pressed if `is_post_freshly_pressed()` is not defined (e.g. on a Jetpack site)

* on a Jetpack site, where we don't mark posts as freshly pressed anyway, `is_post_freshly_pressed()` is not defined, so in the REST API, we shouldn't execute any checks with it if it's not defined.
* adds tests to check that this functionality continues to work as expected in WP.com and that the fatal is fixed in Jetpack
* simplifies/cleans up the Jetpack and Core Post tests

see https://github.com/Automattic/jetpack/issues/1245

Merges r108054-wpcom.
REST API: POST Endpoint: Return featured_image for Jetpack Sites.

Merges r108061-wpcom.
* Allows overwriting the current button style
st flair/sharing: modify the preview function to accommodate for using it in the REST API

I'm adding a REST API endpoint for `meta/sharing-buttons` which provideds the needed meta fo
r managing the sharing buttons for sites. As part of this, I will be generating previews for
 each of the sharing services in the API response. This accommodates the existing preview me
thod for those needs.

* Allows overwriting if the current output is smart or not
* Allows overwriting the current button style
* Allows a param for setting wether to echo or just return the output
* In the admin page: stop echoing the output, since it's already echoed by default by the preview function
* Remove some uneeded whitespace

Merges r107562-wpcom.
Post flair/sharing: add the genericon for each service as a property of each respective class

I'm adding a REST API endpoint for `meta/sharing-buttons` which provideds the needed meta for managing the sharing buttons for sites. As part of this, I want to return the correct genericon to use for each one to make it easier to output previews using the API response.

Merges r107563-wpcom.
Post flair/sharing: remove css styles for digg which are no longer needed since digg has been retired

Merges r107560-wpcom.