analytics: fix bug in isInvoiceAdjustmentItem

We want to look at items on our invoice only.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
util: uniform persistent bus and notifications

* Prefetch a bunch of entries instead of one
* Make notification queue thread pool configurable

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
[maven-release-plugin] prepare release killbill-0.1.75