(new:major) Review back-end logic for keeping track of server connections:
- Added new table "network_connection_stat"
- Added new method "num_connections"

(change:minor) Changed integration with the MySQL back-end transaction management

(new:minor) When the back-end start, the data-store is cleaned (maybe, in the future, add an option to do/avoid this).
(new:major) Added XML-RPC server implementation for MySQL data store.

(change:major) Added new methods to XML-RPC to get connection stats.
- Changed XML-RPC client
- Change XML-RPC server with MySQL back-end
- TODO: change XML-RPC server with SQLite back-end