INT-2934 IntegrationObjectSupport Initialization of ConversionService
- IntegrationObjectSupport: Set a default conversion service in the
  constructor. getConversionService() returns either the
  DefaultConversionService or the integrationConversionService if
  defined.
- AbstractMessageRouter: Deprecate getRequiredConversionService()
- Adjust tests

For further details see
- https://jira.springsource.org/browse/INT-2934
- https://jira.springsource.org/browse/INT-2931