code: function expand(source, opts) {
    opts = opts || {};
    var re = opts.re = opts.re || '.'
      , isre = (re instanceof RegExp)
      , o = {}, k, v, parts, i, p;
    for(k in source) {
      v = source[k];
      if(isre ? !re.test(k) : !~k.indexOf(re)) {
        o[k] = v;
      }else{
        parts = k.split(re);
        p = o;
        for(i = 0;i < parts.length;i++) {
          k = parts[i];
          if(i < parts.length - 1) {
            p[k] = p[k] || {};
            p = p[k];
          }else{
            p[k] = v;
          }
        }
      }
    }
    return o;
  }
docs: Takes a source object with dot-delimited keys
  and expands it to a deep object representation.
  
  Such that:
  
  {'obj.field.num': 10}
  
  Becomes:
  
  {obj:{field: {num: 10}}}
  
  Returns the transformed object.
  
  @param source The source object to expand.
  @param opts Processing opts.
  @param opts.re The string or regexp delimiter
  used to split the keys.