RPC calls needed to add support for Graphene clients to the bts_tools

[wackou]

In order to be able to port the bts_tools to also support Graphene clients, I would need some RPC calls that were available in BitShares 0.9.x but are not yet in Graphene. These are:

• about: needed for info such as tag or git version
• network_get_info: I especially need to be able to get the p2p port on which we are listening
• network_set_allowed_peers: in order to implement the backbone proposal (http://digitalgaia.io/backbone.html) I would need to restrict connections to a set of hosts. In BitShares 0.9.x network_set_allowed_peers used to take a list of peer ids, but those are only available via rpc calling network_get_info on the other client's side. It would be nice if it could take a list of host:port instead. If not, it would be nice if the peer id of another node could be accessible via its public API, such as in the about call, for instance (because the network API is restricted to logged in connections).
• blockchain_get_witness_slot_records: this makes checking whether the delegate missed some blocks very easy (I should probably need to get this info via the websocket api and register for callbacks on the produced blocks, I guess)

It would be really nice if I could get at least the 3 first ones, thanks!