Contact Form: do not display the logged in user's details

Can be overwritten with the jetpack_auto_fill_logged_in_user filter
Fixes #694l
Contact Form: fix spacing

See https://github.com/Automattic/jetpack/pull/725#commitcomment-6888035
Add Filter By Role in Widget Visibility
Update Widget Visibility, add user loggedin filter
Fix translation string and use yoda condition for logged in filter
WP Posts Widget: Add link to the post to the featured image. Fixes Automattic/jetpack#927
Refining the setting of site_tag when twitter:creator is present.

This is an attempt to close #935. I added a class method that
will take in the current value for site_tag and og_tags and
return a new value for site_tag if twitter:creator is set in
og_tags. If nothing is set, it returns the original value of
site_tag.
Merge branch 'master' into use-twitter-creator-for-twitter-site
Move theme support check to `add_setting` argument
Add Customizer section priority

Sets the Customizer section priority below the core sections. Fixes #538
Site Logo: Add the WordPress.com Site Logo feature to Jetpack.

Site Logo allows a user to upload a logo that will persist and be displayed in all themes that support the feature.

WordPress.com support page: http://en.support.wordpress.com/site-logo/

Standalone plugin: https://github.com/Automattic/site-logo
When calling /sites/%s/posts/ include all attachments not just the first 5.
Site Logo: Prefix theme functions.
Site Logos: Update the docblock for jetpack_the_site_logo().
Site Logos: Avoid JS Uncaught Errors in the Customizer when logo objects have no size properties.
Blavatar: Initial adding of the blavatar module
Blavatar: Adding the module so that it shows up in the admin
Blavatar: Add filter that makes sure that all blavatar images get deleted
Update gravatar-profile.php

Remove undefined variable errors
Update image-widget.php

Remove undefined variable errors