Remove Unwanted Pages/Link new calendar

[bbmcmann]

Hospice admins want to remove some current pages which are no longer needed.

• Admin History page
• Remove past shifts/blocked off shift page, and current calendar
• Link the new calendar to the navbar so navigating links us to our new pages
  For this task, remove all references to these pages and their components from App.js, the navbar and any other pages that link to them.
  Do NOT delete the component files themselves, we will keep the old code until we hand off to the nonprofit.