Make the version repo site configurable

Introduce a new value "opkg_repo" in the site configuration.
The value should be a single domain name,
e.g. "http://opkg.services.ffki/attitude_adjustment/12.09/%S/packages".

include/gluon.mk

@@ -12,11 +12,6 @@ BOARD_KDIR = $(BOARD_BUILDDIR)/kernel
 
 export GLUONDIR GLUON_SITEDIR GLUON_IMAGEDIR GLUON_OPENWRTDIR GLUON_BUILDDIR
 
-
-CONFIG_VERSION_REPO := http://downloads.openwrt.org/attitude_adjustment/12.09/%S/packages
-
-export CONFIG_VERSION_REPO
-
 $(GLUON_SITEDIR)/site.mk:
 	$(error There was no site configuration found. Please check out a site configuration to $(GLUON_SITEDIR))
 
@@ -33,6 +28,9 @@ ifeq ($(GLUON_TOOLS),1)
 GLUON_CONFIG_VERSION := $(shell test -d $(GLUON_SITEDIR) && (cd $(GLUON_SITEDIR) && git describe --always --dirty=.$$($(STAGING_DIR_HOST)/bin/stat -c %Y $(GLUON_SITEDIR)/site.conf) 2>/dev/null || $(STAGING_DIR_HOST)/bin/stat -c %Y site.conf))
 export GLUON_CONFIG_VERSION
 
+CONFIG_VERSION_REPO := $(shell $(GLUONDIR)/scripts/site.sh opkg_repo || echo http://downloads.openwrt.org/attitude_adjustment/12.09/%S/packages)
+export CONFIG_VERSION_REPO
+
 GLUON_SITE_CODE := $(shell $(GLUONDIR)/scripts/site.sh site_code)
 export GLUON_SITE_CODE