Allow SSL connections to bitcoind

This is required as, by default, self-signed certificates are rejected as was commented in #436

lib/RpcClient.js

@@ -163,6 +163,7 @@ function rpc(request, callback) {
     path: '/',
     method: 'POST',
     port: self.port,
+    rejectUnauthorized: false,
     agent: self.disableAgent ? false : undefined,
   };
   if (self.httpOptions) {