Fix stupid bug that caused more and more getAux() calls to get scheduled

initialize() is called every time the credentials expire. So every time
that happened, we scheduled another round of getAux() calls. So the number
of API calls per hour keeps going up. Like crazy.

With this commit we a) no longer add more setInterval calls and b) check
inside getAux() if at least 30 seconds have passed since the last time the
API calls have been made.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>