Add support for marking a repository with @Region rather than the entity

[pidster]

An entity marked with @region("regionName") can't be persisted in more than one Region.
This patch permit a repository to be marked with @region as an alternative to the target entity.

[jxblum]

Undo the @SuppressWarnings cleanup commit.

[pidster]

Done.

[jxblum]

Thank you

[jxblum]

Review comments sent in email.

[odrotbohm]

I think the changes in GemfireRepositoryFactory should be simplified to the following pseudocode:

• check repository interface for @Region annotation, if available, use that one
• else fall back to region name provided through GemfirePersistentEntity

As John pointed out in the email, handing a repository interface to the MappingContext is not really using the context as expected.

Another option to consider might be to allow SpEL expressions in the @Region annotation's value attribute to allow people to customize the region something is persisted to on a call by call basis (a thread bound property or the like). MongoDB already supports that, see BasicMongoPersistentEntity for example.

[jxblum]

Closing this PR (#55) in favor of PR #56.