Improvements related to ASF release process (#7539)

* [WiP] Improvements related to ASF release process

* Removing translation binaries (.mo)
* Working on 2 docker files to help package and validate releases
  * Dockerfile.from_tarball: takes a VERSION as input, downloads
    official source release fro svn and bakes it into a functional
    docker image that can be validated
  * Dockerfile.make_tarball: helps a maintainer to package and sign a
    release candidate or release

* Address COPYRIGHT + LICENSE issues

(cherry picked from commit 5ae2836b25)

* Add Roboto font to LICENSE, remove glyphicons files

(cherry picked from commit 9615f39f7a556afe217b4e3288c9116f8ffaab91)

* remove unused LICENSE entries

* Change babytux to open image in birth dashboard

(cherry picked from commit 2776d11893596a029b8af37b96fd6ce1a9f12059)

* Improve instructions

* Docker tweaks

(cherry picked from commit df6e6462458ea8cff1482c142921b20f5607ad8e)

* Include image

RELEASING/make_tarball.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+set -ex
+
+if [ -z "$VERSION" ]; then
+  echo "VERSION is required to run this container"
+  exit 1
+fi
+
+
+echo "version: $VERSION"
+cd /tmp
+git clone --depth 1 --branch $VERSION https://github.com/apache/incubator-superset.git
+mkdir ~/$VERSION
+cd incubator-superset && \
+git archive \
+    --format=tar.gz \
+    --prefix=apache-superset-incubating-$VERSION/ \
+    HEAD \
+    -o ~/$VERSION/apache-superset-incubating.tar.gz
+
+gpg --armor --output apache-superset-incubating.tar.gz.asc --detach-sig apache-superset-incubating.tar.gz
+gpg --print-md SHA512 apache-superset-incubating.tar.gz > apache-superset-incubating.tar.gz.sha512