Fix #3894

* Add separate setting for sidebar text (site_short_description)

* Fix tests

* Redesign landing page (again)

* Move login form in small version to the right column

* Display closed registrations message

* Add site setting for the hero image

* Fix test

* Increase spacing, maximum width, change call to action section

It is faster.

* Improve OpenGraph tags for about pages

* Add thumbnail admin setting

* Fix error

* Fix up

* Add Mastodon::Source.url

* Update spec

* Refactor

Move things frmo Mastodon::Source to Mastodon::Version

* First lame pass at adding optional git commit hash display on /about/more page.

Currently, this is implemented by checking for the existence of a file called CURRENT_RELEASE in the home directory of the user running Mastodon. If the file exists, its contents are added.

I've modified my update process to include the following before precompiling assets:

git log -1 | head -n 1 | cut -d " " -f2 > ~/CURRENT_RELEASE

That puts the current commit hash into the file ~/CURRENT_RELEASE, but you figured that out because you're a smart cookie.

As I am quite sure this is a horrible methodology for implementing this, I look forward to any improvements you have to offer!

* Updated to handle instances that share a user - the CURRENT_RELEASE file now lives in the instance's base directory.

This also requires modifying the update hook to `git log -1 | head -n 1 | cut -d " " -f2 > CURRENT_RELEASE`

* Redesign the landing page, mount public timeline on it

* Adjust the standalone mounted component to the lacking of router

* Adjust auth layout pages to new design

* Fix tests

* Standalone public timeline polling every 5 seconds

* Remove now obsolete translations

* Add responsive design for new landing page

* Address reviews

* Add floating clouds behind frontpage form

* Use access token from public page when available

* Fix mentions and hashtags links, cursor on status content in standalone mode

* Add footer link to source code

* Fix errors on pages that don't embed the component, use classnames

* Fix tests

* Change anonymous autoPlayGif default to false

* When gif autoplay is disabled, hover to play

* Add option to hide the timeline preview

* Slightly improve alt layout

* Add elephant friend to new frontpage

* Display "back to mastodon" in place of "login" when logged in on frontpage

* Change polling time to 3s

* Adds version.

* Cleans up code.

* Removes standalone endpoint and adds version to instance endpoint.

* Addresses feedback from #2181.

* Correct site_contact_email typo

* Separate about more page into partials, add specs

* Add InstancePresenter to expose site details

* Clean up about controller, use instance presenter