The request method should allow functions in body to be able to save design docs correctly

[anton-107]

Example request: databaseClient.request("PUT", designName, designDoc, function(err, data) {} );

Design doc contains functions and they are cut off internally by JSON.stringify. Please, enhance this line:

body = JSON.stringify(body)

with this snippet:

body = JSON.stringify(body, function(key, val) {
  if (typeof val == 'function') {
    return val.toString();
  }
  return val;
});