docs: function isValidField(fieldObj){
          var err,
              props = _.keys(fieldObj),
              mandatoryProps = [
                  '_id',
                  'type'
              ];
  
          if(!_.isObject(fieldObj)) {
              err = new Error('Fields/Meta must be an instance of an object');
          } else {
              _.each(mandatoryProps, function(prop) {
                  if(!_.contains(props, prop)){
                      err = new Error('"' + prop + '" property not found when validating the content type.');
                  }
              });
  
              if(!err && fieldObj._id.indexOf(' ') !== -1) {
                  err = new Error('ids for fields/meta cannot have any spaces.');
              }
          }
  
          return err;
      }