Show "Boundaries" checkbox in Leaflet layer control

This lets users toggle boundaries (e.g. neighborhoods, zip codes) via a checkbox in the Leaflet layers control.
Comment Moderation prototypes

Comment Moderation Page

Needs reviewed by Deb
Merge pull request #1589 from RickMohr/comment-moderation

Comment Moderation prototypes
Merge pull request #1587 from RickMohr/boundaries-checkbox

Show "Boundaries" checkbox in Leaflet layer control
Update scenarios templates CSS.
Merge pull request #1591 from kdeloach/topic/update-scenarios-template

Update scenarios templates CSS.