INT-2970 Update to Spring-AMQP 1.2.0.M1

Add deprecated constants for message properties no
longer used by Spring-AMQP 1.2 (retain to provide
compatibility with 1.1.x).
Merge pull request #777 from garyrussell/INT-2970

* garyrussell-INT-2970:
  INT-2970 Update to Spring-AMQP 1.2.0.M1