General: create standard WordPress templates for various pages

[davekellam]

We may want to spin this out into a series of separate issues, but recording here for now:

• single
• page
• 404
• search
• archive
• etc

[Jessdwilson]

Template for landing pages for departments (special collections) and collections

[kpettinga]

I think we're good here as far as basic templates. If there's more specific ones, let's make a new issue for it.