* add og:url to stream_item view

* add og:url and text to about/show

* add og:url to profile, followers and follows pages

* Adds version.

* Cleans up code.

* Removes standalone endpoint and adds version to instance endpoint.

* Addresses feedback from #2181.

* Simplify render in mailer views

* Simplify render in about/more view

* Simplify render in accounts follow views

* Simplify render in recovery code views

* Simplify render in stream entry embed

* Simplify render in stream entries status partial

* Simplify render in authorize follow new view

* Move site title helper to instance helper (name change only)

* Remove newline in <title> tag

* Add site_hostname helper method to wrap up local_domain value

* Use site_hostname helper in places that need local_domain value

* Correct site_contact_email typo

* Separate about more page into partials, add specs

* Add sprockets-rails to Gemfile

* Add sprockets-rails to Gemfile.lock

* Update show.html.haml

* Update index.html.haml

* Update admin.html.haml

* Update auth.html.haml

* Update embedded.html.haml

* Update public.html.haml

"at least X" and "X or older" have identical meanings.
Using both together feels a little jarring.

related: 1236529e39

Signed-off-by: lindwurm <lindwurm.q@gmail.com>

* Add InstancePresenter to expose site details

* Clean up about controller, use instance presenter

* Add helper method to return Setting.site_title

* Use site_title helper in application layout

* Use site_title value for og:site_name

"Various apps are available" is now a hyperlink

This should help federation

with YAML-defined defaults. Add admin page for editing global settings. Add "site_description"
setting that would show as a paragraph on the frontpage