INT-2526: Remove deprecations in Core after upgrade to Spring 3.1.1

* remove deprecated usage of ConversionServiceFactory.createDefaultConversionService()
* remove deprecated usage of AopUtils.isCglibProxyClass

JIRA: https://jira.springsource.org/browse/INT-2526
INT-2526 - Remove additional deprecations in Core
Merge pull request #735 from sobychacko/INT-2526

* sobychacko-INT-2526:
  INT-2526 - Remove additional deprecations in Core
  INT-2526: Remove deprecations in Core after upgrade to Spring 3.1.1