* Add failing tests for social previews controller. HTML changes between
requests, which breaks caching.
Since we use the HTML to generate the cache key. When the views have any
randomness in them, it breaks the cache, which means we regenerate
images on each request, rather than using what's in memcached.
Adding test to protect from regressions
* Fix randomness in social card templates
The aria tags are randomly generated. Since this is for rendering
images, they aren't needed.
* Make the linter happy by using the sanitize helper
8afb797ec9