Adapt download and Dockerfile to 3.9 release

There's no need to fetch 3.9-SNAPSHOT any more.
Also the download directory for released versions was changed.

Dockerfile

@@ -49,7 +49,7 @@ RUN cp /dev/null /etc/httpd/conf.d/ssl.conf \
 
 # Build arguments
 
-ARG MP_VERSION=3.9-SNAPSHOT
+ARG MP_VERSION=3.9
 ARG MP_DIST_FILE=midpoint-dist.tar.gz
 
 ENV MP_DIR /opt/midpoint

download-midpoint

@@ -6,14 +6,21 @@ if [[ -n "$1" ]]; then
   MP_VERSION=$1
 else
   if [[ $tag == "latest" ]]; then
-    MP_VERSION=3.9-SNAPSHOT
+    MP_VERSION=3.9
   else
     MP_VERSION=$tag
   fi
 fi
-echo "Downloading midPoint $MP_VERSION"
+
+if [[ $MP_VERSION =~ ^[0-9]+\.[0-9]+$ ]]; then
+  URL_BASE="https://evolveum.com/downloads/midpoint/$MP_VERSION/"
+else
+  URL_BASE="https://evolveum.com/downloads/midpoint-tier/"
+fi
+
+echo "Downloading midPoint $MP_VERSION from $URL_BASE"
 echo "-----------------------------------------"
-curl --output $DIR/midpoint-dist.tar.gz "https://evolveum.com/downloads/midpoint-tier/midpoint-$MP_VERSION-dist.tar.gz"
+curl --output $DIR/midpoint-dist.tar.gz "$URL_BASE/midpoint-$MP_VERSION-dist.tar.gz"
 echo "-----------------------------------------"
 echo "Checking the download..."
 if tar -tf $DIR/midpoint-dist.tar.gz >/dev/null; then