3905 Using a tag set with long tags causes challenge sign-up display problems

https://code.google.com/p/otwarchive/issues/detail?id=3905

If you use a tag set for your challenge, and your tag set has a long tag or two, things get ugly on the form. This makes them not get ugly.
(One last time!) 

Put the `<p>` containing the "(See # options)" link inside the `<dd>` because `<p>` tags cannot be direct children of a `<dl>` -- they must be inside either a `<dd>` or `<dt>`. 

Also, the link text was not quite up to our standards: it was in sentence case, it used language that assumes the user is sighted, and it was vague. Now it says "List # Characters" (or Additional Tags, Relationships, whatever).