Update info tab a little
Fix template-related problem

This was preventing the sending of emails for several versions.
Move some calls from database.go to verify.go

Also replace db.DeleteQueuedNode() with db.DeleteExpiredFromQueue(),
which automatically removes expired nodes from the verification queue.

Ref #36
Add "Heartbeat" system for performing DB updates

This means that nodes in the verify queue will actually expire and be
removed after the specified period of time.
Move functions from database.go to cache.go

This commit also adds some functions for mapping local map IDs to public
hostnames. CacheFormatNodes() now uses these functions, and is less
clunky now.

Close #36