* Change icon for domain blocks

Both domain blocks and user blocks uses the same icon…

* Update index.js

* Keep list of blocked domains

Might be overkill, but I'm trying to follow the same logic as for blocked users

* Add basic domain block UI

* Add the domain blocks UI to Getting Started

* Fix undefined URL in `fetchDomainBlocks`

* Update all known users' domain_blocking relationship instead of just one's