Make methods `version` and `orderbook_depth` available without rpc_password

[rozhkovdmitrii]

Impact:

There are methods that are supposed to be available without the RPC password because they do not expose any sensitive or private information. These are the version and orderbook_depth methods.

Todo:

It is necessary to make them available without the rpc password. It would also be useful to find out if the other methods do not disclose confidential information and if they can be set as "public methods".

@shamardy, @smk762

[smk762]

The version method is currently functional without a password. The orderbook_depth method returns {"error":"rpc:215] dispatcher_legacy:135] Userpass is not set!"} in v2.0.0 release