As a FAC grad, I can click a button to log out

[vlbee]

Acceptance Criteria

• Add logout route & oAuth handler - issue Add logout route & oAuth handler #39
• Add logout button to relevant views - issue Add logout button to relevant views #40
• add event listener to logout button wherever it appears - issue add event listener to logout button wherever it appears #41

[helenzhou6]

Relate to user journey: #5