Determine connection between top level events and banner behavior

[froboy]

From #49 (comment)

@froboy @zendoodles the banner (which is consistent to all pages on the site) is set to pull in the site name (MidCamp 2018) and the site slogan (March 8-11, 2018). Should this be set to based on the parent event or should it continue to be based on the site configuration? Since this is a global element throughout the website I think this is a bit more of a content strategy issue than anything else. I think there are bigger questions here, like should the image field be able to change the banner? Should the banner be on every page on the website or just the homepage/parent event page? Can events be three or more levels deep? If so, do all parent events get banners or just first level events?