Added the start of a "what's next" page

Still need to retrieve a list of resources
that are ready to learn but not currently in the map.

See issue #132
Added queries for "what's next" resources

See #132
Added a link for "what's next" resources

The text preceding the link changes depending on whether
the user has completed all previous resources or not
Merge branch 'simplified-ux' into whats-next

Conflicts:
	app/js/maps.js
Merge pull request #149 from kennib/whats-next

Whats next