Update sidekiq config: Allow setting namespace via ENV
Update validator_spec rake task to handle validator sidekiq server
Refactor create post
Refactor: move post mentions/parents/attachments create helpers to PostBuilder
Fix PostBuilder when raising CreateFailure
Fix creating post from notification: Save post with correct entity
Add RelationshipInitiation worker

Triggers the creation of a relationship with specified entity
Handle subscription creation, Triggers relationship initiation if one doesn't exist
Fix race condition for Entity.first_or_create
Fix relationships unique constraint
Update subscriptions db schema
Handle subscription notification
Update relationship initiation
Update subscription creation
Notification dispatch handles subscriptions