[Settings] Update: Save, monitoring, notification

Make settings & white list independant.
Settings doesn't call directly WhiteList API.

Settings 'never_quit' & 'netf_enabled' & 'netf_entries' are now save to the settings file
when set using the new API below:

- dleyna-settings_set_never_quit
- dleyna_settings_set_white_list_enabled
- dleyna_settings_set_white_list_entries

Monitoring has been removed.

Signed-off-by: Ludovic Ferrandis <ludovic.ferrandis@intel.com>