db: remove constraints in cybersource_transactions

This is to match the killbill generator 3.1.8.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
api: make payment calls idempotent

Use the CyberSource OnDemand API to make payments idempotent.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Merge branch 'master' of github.com:killbill/killbill-cybersource-plugin

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>

Conflicts:
	killbill-cybersource.gemspec