* common/Monitors.cpp, common/Monitors.h: Add a new class to handle
storing key value pairs useful in monitoring the state of a server.
* server/HttpCache.cpp, server/HttpCache.h: Add a function argument
to allow the content type to be controlled in the header.
Expose the Monitors class under /monitors URL.
* server/HttpCache.cpp, server/HttpCache.h: A caching file to handle
http data requests.
* server/CommHttpClient.cpp, server/CommHttpClient.h: Move most of
the functionality into HttpCache.
