Initial change for catalog xml to suppport usage billing
Add limits to Usage section
Introduction of catalog recurring BillingMode
Catalog usage APIs
API changes for usage billing consumable in arrear
Add usageName in invoiceItem (ddl change)
Revert pom to SNAPSHOT
pom.xml: updates for release 0.8.3

Api modifications for usage initial work

Signed-off-by: stephane brossier <stephane@ning.com>
Add missing copyrights