Workaround async weirdness

async.forEachSeries sometimes seems to call the iterator without any
argument, causing syncClass to be undefined. This workaround makes sure
that this doesn't cause any trouble.

Fixes #105.
Avoid sync in test suite

Sync will be tested on its own, right now it can only cause trouble if a
sync starts running while doing tests.
Atoms are only in /posts and /status

Fixes #101.