Cool spring configuration

Foundation for using cool spring property configuration much more elegantly.

This in itself doesn't "do" anything yet. I'll use it on SMS branch to configure gateways etc. You could use it e.g. to write ContentRepositoryFactory.createS3DocumentStore() more Spring-like - instead of (delete) S3CredentialsData/ExternalServicesReadPlatformService/ExternalServicesReadPlatformServiceImpl/ExternalServicesConstants, you should be able to simply use (I haven't tried it) @Value("${"s3_access_key"}") etc. in S3ContentRepository!