Update signed-out behavior to hide all projects except for the currently open one, if any.  This behavior is consistent whether the user clicked the sign out button, or timed out their session.
Update signed-out behavior to hide all projects except for the currently open
one, if any.  This behavior is consistent whether the user clicked the sign
out button, or timed out their session.

Fixes #107

pranjaltale16/codeworld,nomeata/codeworld,google/codeworld,nomeata/codeworld,tgdavies/codeworld,google/codeworld,stefan-j/codeworld,three/codeworld,stefan-j/codeworld,parvmor/codeworld,parvmor/codeworld,parvmor/codeworld,stefan-j/codeworld,alphalambda/codeworld,alphalambda/codeworld,alphalambda/codeworld,pranjaltale16/codeworld,venkat24/codeworld,venkat24/codeworld,three/codeworld,tgdavies/codeworld,tgdavies/codeworld,venkat24/codeworld,google/codeworld,three/codeworld,nomeata/codeworld,pranjaltale16/codeworld