Changed cache.py to only delete changed level from cache
Changed cache.py to only delete changed level from cache

Fixes #477

CelineBoudier/rapid-router,mikebryant/rapid-router,mikebryant/rapid-router,mikebryant/rapid-router,CelineBoudier/rapid-router,CelineBoudier/rapid-router,mikebryant/rapid-router,CelineBoudier/rapid-router