Cache tag data on client-side

[jefflunt]

• See if there's a way to load all tags in a LogBook the first time you're browsing the various sections of a LogBook
• Consier storing this information locally using HTML5
• The local cache must be invalidated when a new WorldObject is added (i.e. when new tags are created)
• The auto-suggest tagging feature needs to gets its values from the cached data, rather than hitting the DB for an AJAX call
• It'd be nice, when you create a new object, to simply add it to the list of cached items, rather than having to re-download the whole cache all over again
• It'd be nice, when you delete an object, to simply remove it from the list of cached items, rather than having to re-download the whole cache all over again