Couchbase-CLI should display the error message returned by ns_server

Issued graceful failover using couchbase-cli. Command failed as expected.
Couchbase-cli displayed the error code returned by ns-server but not
the error message.

E.g.
Error message displayed by couchbase-cli is "No JSON object could be decoded" where as the actual message returned by ns-server is "Rebalance running." If the command is issued using the REST interface, then it displays the correct error message. Same issue was seen with other failover errors as well.

------------ Command issued using CLI -----------------
couchbase-cli failover --server-failover=127.0.0.1:9002 -c 127.0.0.1:9000
ERROR: unable to failover n_2@127.0.0.1 (503) Service Unavailable
ERROR: command: failover: 127.0.0.1:9000, No JSON object could be decoded

------------ Command issued using REST -----------------

/Users/poonam/Workspace/Sherlock/couchbase-cli$ curl -v -X POST -u Administrator:asdasd http://127.0.0.1:9000/controller/startGracefulFailover -d otpNode=n_2@127.0.0.1

• About to connect() to 127.0.0.1 port 9000 (#0)
• Trying 127.0.0.1...
• Adding handle: conn: 0x7f8599801a00
• Adding handle: send: 0
• Adding handle: recv: 0
• Curl_addHandleToPipeline: length: 1
• - Conn 0 (0x7f8599801a00) send_pipe: 1, recv_pipe: 0
• Connected to 127.0.0.1 (127.0.0.1) port 9000 (#0)
• Server auth using Basic with user 'Administrator'
  > POST /controller/startGracefulFailover HTTP/1.1
  > Authorization: Basic QWRtaW5pc3RyYXRvcjphc2Rhc2Q=
  > User-Agent: curl/7.30.0
  > Host: 127.0.0.1:9000
  > Accept: /
  > Content-Length: 21
  > Content-Type: application/x-www-form-urlencoded
  >
• upload completely sent off: 21 out of 21 bytes
  < HTTP/1.1 503 Service Unavailable
• Server Couchbase Server is not blacklisted
  < Server: Couchbase Server
  < Pragma: no-cache
  < Date: Wed, 25 Mar 2015 18:05:29 GMT
  < Content-Type: text/plain
  < Content-Length: 18
  < Cache-Control: no-cache
  <
• Connection #0 to host 127.0.0.1 left intact
  Rebalance running.