Enhancement: stratum.Client should support client.* calls to client from server

[jla415]

example from server to stratum.Client:

{"id": 1289739, "method": "client.get_version", "params": null}.

Currently the library just throws an exception here:

node-stratum/src/client.ts

Line 151 in c4decc5

throw new Error("No suitable command was issued from the server");

see:
https://en.bitcoin.it/wiki/Stratum_mining_protocol#Methods_.28server_to_client.29

Would be nice to be able to handle and respond to various client.* requests from the server...

[pocesar]

yes, I'm going to cover the new protocol changes, the initial version was using slushpool's in 2013