Handle malformed JSON returns

[remingtonc]

Malform JSON can be returned in errors, etc. Need to handle these problems.

{
   "rpc-reply" : {
      "rpc-error" : {
         "error-type" : "protocol",
         "error-tag" : "unknown-namespace",
         "error-severity" : "error",
         "error-message" : "Namespace="http://openconfig.net/yang/interfaces""
      }
   }
}

NXOS: version 7.0(3)I7(3)