Show/Hide toggle for discussion text

[cjlee112]

For any page that accumulates results over time, showing full text for all those results quickly becomes un-navigable. Obvious examples: person (will grow linearly as a function of time); topic (might grow as a higher power of time if we manage to index / attract increasing numbers of people). So for a start I think we should apply the Show text toggle that we first used on the Comment Search results page to

• person page
• topic page
• paper page

[cjlee112]

use the same toggle control mentioned for issue #62