support options with labels only

[SailorMax]

Summary

Add support of options without text, but with label

Please double-check that:

• All changes were made in CoffeeScript files, not JavaScript files.
• You used Grunt to build the JavaScript files and tested them locally.
• You've updated both the jQuery and Prototype versions.
• You haven't manually updated the version number in package.json.
• If necessary, you've updated the documentation.

See the Pull Requests section of our Contributing Guidelines for more details.