Sso openam

Dear geonetwork contributors,
I have implemented support for OpenAM on SSO via spring security. As this implementation is based on a openSSO-springsecurity jar file, here is a first pull request to add the library to maven_repo. If it is OK , I will then send another pull request for the rest of the development (on the core_geonetwork 2.10.x ).
Best regards
Thierry Chevallier