Sign Out button in header.component.ts is changed with an associated event on click
authenticate.ts includes the behavior when user tries to sign out.
If the user has uncommitted changes or unpushed commits, a warning message will show up. User can choose to remain on the same page, or sign out anyway which redirects the user to the home page.
If nothing prevents sign out, user is also redirected to the home page.
Coordinated with issue #29 on bringing up warnings upon sign out.
Also completely resolves issue #72, because the 're-sign in' situation cannot happen now that sign out button redirects to home page.
Coordinated with issue #29 on bringing up warnings upon sign out. Also completely resolves issue #72, because the 're-sign in' situation cannot happen now that sign out button redirects to home page.
Closes issue #7