http://www.developer.com/java/ent/extend-spring-security-to-protect-multi-tenant-saas-applications.html
https://scotch.io/bar-talk/bootstrap-3-tips-and-tricks-you-might-not-know
http://massimilianosciacco.com/handle-permissions-spring-security
http://springinpractice.com/2010/10/27/quick-tip-spring-security-role-based-authorization-and-permissions
http://dtr-trading.blogspot.tw/2014/04/spring-security-32-users-roles_7532.html
http://stackoverflow.com/questions/25971979/spring-security-acl-doesnt-compare-bitwise-permissions