Changed artifact name of security project
Polish
Consolidated UserIdExtractor and UserIdSource in core, requiring adjustments in Spring Social Samples
Added XML-configured variety of Spring Social Showcase using SocialAuthenticationFilter
Converted all JavaConfig to XML for XML-based showcase sample (previously, only the social configuration was in XML).
Create in-config user ID source to avoid unnecessary dependency on spring-social-security.
Sync'd examples up with latest changes, plus included an XML-configured example using SocialAuthenticationFilter