Fix HTML closing tags.
Add mandatory selection option.

Add a mandatory selection config option that (if enabled) preselects
the first tag and hides the clear ("x") button. Useful if you want to
force a choice to be made. Also added to example page.
Merge pull request #1 from benbasson/master

Add mandatory selection option.
Merge pull request #8 from benbasson/upstream

Fix HTML closing tags.