testing: Config changes for FreeRADIUS 3.0

Also includes some changes for jessie's version of FreeRADIUS 2 (was
previously a custom version).

Besides the move to a subdir the config files were adapted for 3.0.

The rlm_sim_files module was removed with FreeRADIUS 3 and Debian's
package of FreeRADIUS 2 does not ship it, so we now replicate it using
the files module (via users file, which is actually a symlink to
mods-config/files/authorize in the default installation of FreeRADIUS 3).
Another approach was tried using rlm_passwd, however, that module does
not read binary/hex data, only printable strings, which would require
changing the triplets.
For 2.x a hack in the site config is necessary to make the attributes
available to the EAP-SIM module.

testing/hosts/alice/etc/freeradius/3.0/clients.conf

@@ -0,0 +1,5 @@
+client moon {
+  ipaddr = 10.1.0.1
+  secret = gv6URkSs
+  require_message_authenticator = yes
+}