[btcsuite/btcwallet] 97963b: Update README for gRPC changes.

[Josh Rickmar]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcwallet
  Commit: 97963b47cee10376f410db4a095a841f453ce0e0
      
https://github.com/btcsuite/btcwallet/commit/97963b47cee10376f410db4a095a841f453ce0e0
  Author: Josh Rickmar <jr...@companyzero.com>
  Date:   2016-02-09 (Tue, 09 Feb 2016)

  Changed paths:
    M README.md

  Log Message:
  -----------
  Update README for gRPC changes.

While here, remove mention of btcgui and add a disclaimer that total
compatibility with the JSON-RPC server cannot be achieved.