Restore Apache::Session::Generate::MD5 as this is a bugfix of #LEMONLDAP-357 (#LEMONLDAP-581)

git-svn-id: svn://svn.forge.objectweb.org/svnroot/lemonldap/branches/lemonldap-ng_version_1_2-bugfixes@2749 1dbb9719-a921-0410-b57f-c3a383c2c641