Implement Citadel Asset Listings

[mglinski]

Implements Citadel Information Lookups using the stop.hammerti.me.uk structures api.

[whinis]

Hey thanks for this, but I would personally like it if it didn't download a 1Mb json file essentially every request. Before I would merge this I would want some sort of caching on this beyond storing it for the current request. That way its only downloaded once a day or month perhaps.

As far as I can see there really isn't a nice "public" caching function but within the next couple of weeks there should be one for my ESI rewrite.

[whinis]

Not sure if you are still monitoring this however I recently added the first part of the ESI update which includes a new caching class almost specifically for this reason.