Refresh services from conf endpoint daily

[0pcom]

Daily service refresh / refetch

With the addition of whitelist-based authentication for survey collection, which is a requirement for rewards, it's important that the whitelist of keys which can collect the surveys always reflect those keys which are designated by the conf service. Otherwise, it will not be possible for the survey to be collected.

More generally, it's important that the visor's config reflect the services in the service conf endpoint soon after any changes are made to that endpoint.

We should not burden the user with regenerating the visor config if the service conf endpoint is updated; it should happen automatically to the extent possible.

Service conf over dmsg

It may be prudent, also, to allow the service conf to be accessed over dmsghttp as the other services are.

Include service conf URL / pk:port in visor config

It may be necessary to allow an array of service conf URLs (i.e. conf.skywire.skycoin.com) and / or the dmsghttp server pk:port which would serve the conf endpoint over dmsghttp to be specified in the visor's config & to skywire-cli config gen

dmsghttp-config.json refresh over dmsg

Additionally, it may be desirable to provide the dmsghttp-config.json over dmsg instead of exclusively distributing that as a file with every release, as any updates to that config technically require either a new release of the software or otherwise manual intervention on the part of the user to update.