Restructure jquery/ui directory, add i18n
Some form improvements

- Implement jquery-ui datepicker in Dateselect
- Rework Radio and Checkbox to support attributes
Cleanup
Another tweak to @method in doc block

The methods getImgUrl() and getImgTag() are used in multiple services, but some have additional parameters. This is an attempt to document them so that tools like scrutinizer-ci won't complain about the magic method calls generated by every service consumer.
Fix empty button title, and empty placeholder attribute in DateSelect
Fix issue in Radio form element
Merge pull request #204 from geekwright/jquidate

Some form improvements and cleanups