feat(district): few more geo feature collection and election page improvements

...istrictgeofeaturecollectionpage_content_after_and_more.py

district/models.py

...t/templates/district/district_election_campaign_page.html

...plates/district/district_geo_feature_collection_page.html

...templates/styleguide/2.3.x/blocks/three_column_block.html

...d/templates/styleguide/2.3.x/blocks/two_column_block.html