Refactor App.js to use if else instead

[SirrorsMoore1975]

• Get rid of the horrifying () ? () : () in App.js into using if - else loop

[SirrorsMoore1975]

I am also fixing Nav bar signup button to be displayed at logout, hide when it is in the login page on the same branch.

Nicole is working on login and logout, but logged in is also when signup should not appear.

Maybe turn this into another issue later.