Minor changes

• Changes to support slots API refactoring (commit by JasonGore, pr #8754)

Patches

• Update Calendar and DatePicker import paths (commit by ecraig12345, pr #9253)
• Update and dedupe React deps. (commit)
• Support slots API changes. (commit)
• Nav, Calendar, and DatePicker move into office-ui-fabric-react (commit)
• Update Router imports (commit)