Deletes all entries in the cache area

def reset(self):
        """Deletes all entries in the cache area"""
        if self.collname not in self.current_kv_names():
            return # nothing to do
        # we'll simply delete the entire collection and then re-create it.
        r = self.request('delete',
                         self.url+"storage/collections/data/"+self.collname)
        r.raise_for_status()
        self.initialize()