code: function (db, entityName, doc, cb) {
  			request.post({
  				url: host + 'databases/' + db + '/docs',
  				headers: {
  					'Content-Type': 'application/json; charset=utf-8',
  					'Raven-Entity-Name': entityName
  				},
  				body: JSON.stringify(doc)
  			}, function (error, response, resBody) {
  				if (!error && (response.statusCode === 201 || response.statusCode === 200)) {
  					var result = JSON.parse(resBody);
  					cb(null, result);
  				} else {
  					cb(error || new Error(response.statusCode), null);
  				}
  			});
  		}
docs: Stores given document, returns raven generated id in callback.
  @param {string} db
  @param {string} entityName
  @param {Object} doc
  @param {Function} cb