Cleanup pending assignment map removal in UniqueId.
Fix a possible bug in the race condition return logic where the wrong deferred
was being returned.

Signed-off-by: unknown <clarsen@euphoriaaudio.com>
#259: TSDB.collectStats(StatsCollector) will relay collect stats to plugin instances.

Signed-off-by: unknown <clarsen@euphoriaaudio.com>
#260: Fix for UIDMeta.getStorageJSON() which fails when custom is not null.

Signed-off-by: unknown <clarsen@euphoriaaudio.com>