Diversify seednode hosting and ownership

[erciccione]

Currently, all seednodes are hosted by the Firo team and hosted on the same vps provider. This should be avoided and for resilience and censorship-resistance i suggest to:

1. Host seednodes on multiple vps providers. In case of the vps provider going down for any reason, people will not be able to connect to the Firo network, which will result inaccessible to anyone who is not already connected to it. It's very important to have seednodes hosted by different vps providers.
2. Give the possibility to the community to host a seednode. Not as critical as 1, but allowing trusted community members to run and maintain seednodes will result in these servers being spread on multiple platforms, countries, providers. Making the network more solid.