Create Browse Exhibits page

[eam5]

Continue work on creating a public Browse Exhibits site page, added to site through site navigation settings. Follow up with work from 338b5f147f54a42136209e46df15308575f27f7f

Neatline Browse requires:

• ability to filter exhibits for specific site (?)
• create list of filtered public exhibits
• create links to exhibit show pages (see next issue, Create Exhibit Show page)