merges child options up with the parent options object Example: obj = {a: 1, b: {a: 2}} mergeOpts(obj, 'b')  Returns: {a: 2}
function _mergeOpts(allOptions, childFieldName) {
  var finalOpts = {};
  allOptions = _normalizeOpts(allOptions);
  var name;

  for (name in allOptions) {
    if (name !== childFieldName) {
      finalOpts[name] = allOptions[name];
    }
  }

  //merge in the per type settings for the childFieldName
  if (childFieldName && allOptions[childFieldName]) {
    for (name in allOptions[childFieldName]) {
      finalOpts[name] = allOptions[childFieldName][name];
    }
  }
  return finalOpts;
}