Facebook deprecated their v1.0 API and thus the old ones no longer work (for new authorizations).

closes #6019 [ci skip]

closes #6014

and cleanup the code so it follows the code guidelines

closes #5955

closes #6028

closes #6020

closes #5924

The <hr> tag in the markdown-content was #eee,
and thus almost invisible. It has been changed to
$border-gray (currently #ddd) to be consistent
with the other <hr> tags.

Adjust markdown-content hr style further

The hr tag is now centered at 85% width. It also
adds a default vertical margin that is equivalent
to the 0.8em the paragraph tags provide.

Refactor scss for markdown-content hr

Closes #6016

See https://github.com/bundler/bundler/issues/3697

closes #6013

closes #6009

closes #6007

closes #6005

- move mobile icons to mobile-folder, so they aren't included in the
  icons-sprite
- move logos to branding/logos, and create a logos-sprite without the
  big other branding-images
- delete duplicate images

closes #6004

Remove unnecessary initializer and comments in Gemfile and add explicit rubyzip gem version in Gemfile with description

closes #6001

closes #5991

closes #5998

closes #5994

closes #5992

closes #5989

closes #5988

Since the Facebook API has changed and additional permissions are required for all users on a pod to cross-post, an additional 'authorized' flag is needed to be set for the Facebook service.
This flag allows either all users, one user or no users to use the cross-posting service.

Clarifies the situation for #5923, #5260 and #5085.

closes #5985

closes #5986

closes #5983

closes #5978

closes #5975

regression from 1da1c53f203e6eb9dad50872e573a4965219ef92

closes #5976

last renamed in 8386179f

closes #5970

closes #5968

closes #5967

closes #5966