Avoid the creation of temporary objects in the GemfireTemplate when used with Spring Data GemFire's Repository abstraction and extension.

Currently, the org.springframework.data.gemfire.GemfireRepository class creates temporary callback objects (GemfireCallback) delegating to the GemfireRepository.execute(:GemfireCallback) method.

Each user-defined, GemfireRepository extension created by an application is backed by the SDG SimpleGemfireRepository base class as well as the GemfireTemplate, potentially causing a large number of temporary callback objects being created based on an applications usage pattern with the Repository.