The noticeboard listens for updates to user assignments (including who
was previously assigned the device), but was requesting data which no
longer existed (as updates are delayed and buffered for up to 500ms).
Migrate all SignalR 1.x Persistent Connections to SignalR 2.x Hubs.
Abstracts ScheduledTaskStatus with core interface and adds a Mock for
optional status reporting. Noticeboards rewritten (with new theme) to be
more resilient and accurate.