Merge pull request #164 from LaurentGoderre/update-variant-detect

Reused the variant detection code from the test-build script

update.sh

@@ -14,7 +14,9 @@ for version in "${versions[@]}"; do
 		continue
 	fi
 
-	for variant in default onbuild slim wheezy; do
+	variants=$(ls -d $version/*/ | awk -F"/" '{print $2}')
+
+	for variant in $variants; do
 		template="Dockerfile-$variant.template"
 		dockerfile="$version/$variant/Dockerfile"