Fix styling and usage of gridism.

- Add no-gutters to most grids to remove padding.
- Set style for h4 under article elements.
- Wrap in unit.whole at article level.
Update Header partial to remove nav and add date.

- Remove the navigation from header.
- Add a date element in place of nav.
- Change to use half units in header.
- Add responsive changes for phone view of date.
Add no-gutters to align all sections.
Change usage of gridism to fix layout issues.

- Wrap each new section in a grid to follow how gridism should work.
- Remove unused CSS.
- Change element names and corresponding CSS styling.
Resolve conflict in merge with CK's code.

- File conflict in index.html.slim.