Add libjpeg-turbo build, add build_tag support

builder/test-deb

@@ -5,10 +5,11 @@ set -e
 cd "$(dirname "$0")"
 . ./os_ver_cli.sh
 
+tester_image=kasmvnctester_${os}:$os_codename${build_tag_for_images}
 docker build --build-arg KASMVNC_PACKAGE_DIR="build/${os_codename}" \
-  -t kasmvnctester_${os}:$os_codename \
-  -f dockerfile.${os}_${os_codename}.deb.test .
+  -t "$tester_image" \
+  -f dockerfile.${os}_${os_codename}${build_tag}.deb.test .
 docker run -it -p 443:8443 --rm \
   -e KASMVNC_VERBOSE_LOGGING=$KASMVNC_VERBOSE_LOGGING \
   -e "VNC_USER=foo" -e "VNC_PW=foobar" \
-  kasmvnctester_${os}:$os_codename
+  "$tester_image"