[rpc] This needs to be converted to use v2 of the btcjson package.

[davecgh]

As the title indicates, the main daemon, and any sub-packages which make use of btcjson, need to be converted to use v2 of the package. Version one of the package is deprecated and will be going away soon.

See btcsuite/btcd#314 for the pull request which converted btcd to use the package. The changes here will be substantially similar.