Fix missing foaf: prefix in prefs.ttl

Author: dmitrizagidulin

default-templates/new-account/settings/prefs.ttl

@@ -1,5 +1,6 @@
 @prefix dct: <http://purl.org/dc/terms/>.
 @prefix pim: <http://www.w3.org/ns/pim/space#>.
+@prefix foaf: <http://xmlns.com/foaf/0.1/>.
 
 <>
   a pim:ConfigurationFile;