Feature overview / feature list page

[localjo]

This branch will resolve #718, #719

Is also adds the routes and templates needed for #720 #721

[localjo]

@russbiggs The basic layout for the features page, and the design changes are in this PR.

The attributes completeness numbers are still static, and there is no data on the map yet. Which data should the map show on this page?

[localjo]

@russbiggs To test this branch, add the following keys to each of the features in campaign.json

"feature_count": 42,
"complete": 13,
"incomplete": 29,