organize sidekiq jobs into logical queue names

https://assembly.com/coderwall/bounties/422

SearchSyncJob must use search_sync queue for uniqueness

SearchSyncJob depends on its queue being its own queue, because that is
how it enforces uniqueness
Merge pull request #247 from codebender/reorg_sidekiq_queues_422

Split up Sidekiq work across more specific queues. #422