New plugin top for top processes

Hello,

This plugin works on the "agent" side and sends "ps" (process list) to the server as a notification.

It is supposed to be used by new write_top plugin (see pull request #260 about write_top).

JsonRPC plugin (pull request #154) was updated for easier use of this plugin.

Credits to Cyril Feraudet who initially wrote this plugin.

Regards,
Yves