Zabbix

...G...... [ZBXCTR-2] added support of username/password parameters like it's done in other plugins and did some refactoring:
                      * added session support. Sessions were read from configuration, but not used.
                      * added connection string assembly using url.URL structure. This ought to take care about encoding special characters in passwords etc.
                      * added key parameter to handler functions to avoid overwriting session/url with key to pass it to the handler.
                      * changed age/size queries to use parameter instead of printing the value inside query.