* add og:url to stream_item view

* add og:url and text to about/show

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

Create MediaAttachment but without actual file download when domain is blocked with reject_media set to true
Clean up old media files when creating a new domain block with reject_media set to true
Return remote_url in media attachments API if local file is not present
Undo domain block action in admin UI
Ability to enable reject_media from admin UI

* Add option to disable verify partial doubles

* Add show_landing_strip? helper method

* Use show_landing_strip? helper in accounts and stream entries views

* Fix naming in view specs

as suggested, moving to view tests rather than a controller test
replaces https://github.com/tootsuite/mastodon/pull/1786 which i will
close momentary