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
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
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
Blavatar: bug fix uploading the image with the same name resulted in the same image being deleted
Typo fixes, Making instance a class property
Blavatar: Fixes PHP Error
Blavatar: Code Clean up

- Seperated Functions into its own file
- Added Private & Public methods
Blavatar : Made admin_init public
Site Logo: Sanitize header text classes for output.
Merge branch 'master' of github.com:Automattic/jetpack into site-logo-escaping