Re-organized widgets.

- changed maxValues to maximumValues to be consistent
  with the naming standards of this app.
- instead of parsing data-*, yourlabsWidget parses data-widget-*,
- deprecated autocomplete_js_attributes and widget_js_attributes
  in favor of attrs (for input) and widget_attrs (for widget
  container)
- fixed bugs in constructor and wrote tests.
Fix #84: Placeholder is gone from yourlabs.Autocomplete, use input attr instead