Spring social support - Reinstatement

Support for the /me endpoint required to support Spring Social clients ( SECOAUTH-352 )was removed in commit 9e408e994b1547de2f3e187899e424fd70cb98c3 as part of Java config refactor.

I've made the necessary changes required to reinstate the support for the /me endpoint - this allows spring-social-sparklr module ( https://github.com/michaellavelle/spring-social-sparklr ) to obtain profile details for currently authenticated user, and therefore permits "login with Sparklr" functionality in Spring Social apps.