Make HTTPDUSER optional

Makefile

@@ -7,7 +7,7 @@ LOCALE_DIR     := locale
 LOCALES        := nl_NL
 GETTEXT_DOMAIN := archery
 
-include config.mk  # defines HTTPDUSER
+-include config.mk  # defines HTTPDUSER
 
 SCRIPTS := $(patsubst %,$(WWW_DIR)/js/%.js,$(SCRIPTS))
 STYLES  := $(patsubst %,$(WWW_DIR)/css/%.css,$(STYLES))
@@ -53,6 +53,9 @@ min: static
 
 $(CACHE_DIR):
 	mkdir -p $@
+ifneq ($(HTTPDUSER),)
+	setfacl -R -m u:$(HTTPDUSER):rwX -- $@
+endif
 
 # Gettext translations