Security openam

Dear all, 
this pull request for geonetwork:2.10.x is about OpenAM SSO configuration via spring security ( 8 commits ). This evolution has been implemented in the context of the ingeoclouds project. The content :
- new package :  org.fao.geonet.kernel.security.openam
- new configuration files : config-security-openam.xml and AMConfig.properties
- update of existing configuration files (only to ease openam configuration, no change in default configuration) : config-security.xml and config-security.properties
- reference to required libraries : in web/pom.xml and maven_repo (cf. corresponding pull request)
Best regards
Thierry