Add jetpack_no_publicize_post filter

Allows plugins to prevent particular posts from being sent to publicize. Ref #7
Tidy up new filter for disabling publicize on a post.

Follow-up to 4b741e2e702a2fb8ba14afa66a0f121e78ef3391

Whitespace fixes, renaming the filter to something that makes it a bit
more understandable, and pass the post’s data across with it.

Also converting to Core’s new recommended brace syntax.
Revert "Tidy up new filter for disabling publicize on a post."

This reverts commit 8ed18b1eef0c2b9dfdbaab0d8efdfec05ce20b1c.
Revert "Add jetpack_no_publicize_post filter"

This reverts commit 4b741e2e702a2fb8ba14afa66a0f121e78ef3391.
Jetpack: Update theme compat includes function to only require compat
files necessary for the current theme.
Jetpack: Add Twenty Fourteen compatibility file for Featured Content and
Post Flair.
Jetpack: Set 'featured' as the default tag name in the customizer for
Twenty Fourteen.
Jetpack: SSO: Consolidating wording to 'two step'

Consolidating 'two factor' and 'two step' to be 'two step' to align with wording on https://wordpress.com/settings/security/