Status

Status as mentioned in #119, excluding connections as discussed on irc.

Fairly standard stuff. Only rough thing is cache size. For memory cache, it's a rough estimate, probably a bit on the low end, based off the SKIN_SIZE const and bow many members are the in usernames slice. For Redis cache, we send the INFO command get the entire memory usage of the Redis instance, which'll be a slight overestimate as that includes Redis' own operating memory.

Gives a JSON response like follows. Memory is all given in bytes, uptime in seconds:

```json
{"Memory":355816,"Uptime":5345,"Served":{"bust":2},"CacheHits":1,"CacheMisses":1,"Cached":16384}
```