A11y: chosen-single link should have role="button"

[juanolalla]

Accessibility alerts about the following error: Anchor element found with link content, but no href, ID or name attribute has been supplied.

Steps to reproduce

Just configure chosen and inspect the code around the drop-down item. Everything is wrapped in the "chosen-single" class link with no href, id or name.

Expected behavior

The link <a class="chosen-single"> should be a button if it is an action. Converting it into a button would have a great impact on the library, so I suggest just to add role="button" as attribute to this link.

[juanolalla]

Fixed in pull request: #53

[juanolalla]

Added a commit to complete the implementation. Now it also adds an aria-label to inform screen readers what will happen if you click the button, "Show options" or "Hide options". It hides the visual arrow up/down indicator container from screen readers with aria-hidden.