Implemented a caching API to query chunkserver status

The metaserver ping function has been modified to include a caching system. The ping function itself has also been modified to return a Status object instead of modifying the Status passed as a parameter. The cache refresh time is 30 seconds, but will not refresh unless a user asks for data. The added queries will pull information from the cache.
The three new queries are:
- /query/stats/<hostname/ip>
  - Displays all of the attributes for any UpServer instance
- /query/dead/<hostname/ip>
  - Displays the current status of any server, and also the entire disconnect history
- /query/dead/count
  - Displays all of the servers that have any recorded disconnects and their disconnect counts