libtorc-core: Add TorcRPCRequest
libtorc-core: Small refactor of TorcHTTPRequest/Service
libtorc-core: Refactor HTTP handlers in TorcHTTPServer

- remove copious locking and thread safety mechanisms when using http
handlers. At the end of the day, a 'client' needs to hold both the
server and handler lock, so no need for all the safeguards.

- instead, make the handler list static, so a client needs to hold just
the handler lock and makes service/content calls independant of the web
server (which will be required for RPC calls over TorcWebSocket)