Ongoing payment implementation
Payment state machine debug and fix retry tests
Merge remote-tracking branch 'origin/state-machines2' into platform

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

Conflicts:
	payment/src/main/java/org/killbill/billing/payment/glue/DefaultPaymentService.java
	payment/src/test/java/org/killbill/billing/payment/PaymentTestSuiteNoDB.java
	payment/src/test/java/org/killbill/billing/payment/glue/TestPaymentModule.java
	payment/src/test/java/org/killbill/billing/payment/glue/TestPaymentModuleNoDB.java
	payment/src/test/java/org/killbill/billing/payment/glue/TestPaymentModuleWithEmbeddedDB.java