https://issues.jboss.org/browse/APIMAN-105

- New beans representing a Policy and PolicyFailure

- New asynchronous interfaces to more generically handle async events

- Policy and policy chain related interfaces

- Refactor engine interface, and temporarily stub implementation to work with new async interfaces
Merge pull request #21 from msavy/initial-apiman-core-interfaces-2

https://issues.jboss.org/browse/APIMAN-105 (2)