Make the 'delay' option effective when set from the server config

The remote watcher uses the 'delay' option (in seconds) between 2 calls to the NuxeoDrive.GetChangeSummary operation. That value can be tweaked from different locations: from the CLI using the --delay argument from the local config file from the server config The last possibility was not working: if one set the 'delay' option to another value different from the default, the option will effectively be updated but not used by the remote watcher. A fix had been merged to use the new value as soon as available, making the remote watcher adapting its calls in realtime.