Dump result from vSphere Agents to JSON only if *no* helper was used

* The vPoller Helpers should be used when we need to perform
  any data translation, e.g. terminating data for C clients
vPoller Zabbix Helper: Dump any result to JSON before returning to client
Initial commit of the vpoller.helpers.czabbix helper module for C clients
Initial commit of the vpoller.helpers.cclient helper module for C clients
vpoller-cclient: By default we use the vpoller.helpers.cclient helper
vPoller loadable module for Zabbix uses the vpoller.helpers.czabbix helper