404 page

First iteration of the 404 page, Fixes https://github.com/DoSomething/dosomething/issues/3289 

*Missing final title/copy for the default node*
I'd recommend naming this based on the semantic contents of the tag, rather than using a `.center-text` class universally to apply styles. That way, if we decide to change how something looks in the future, we know to go to the CSS to make visual changes.

In this case, it looks like `results-info` might be a good class name. :)