docker: Added script to generate official-images/library/tusd file. (#289)

* Added script to generate official-images/library/tusd file.

* Moved script to .scripts.

.scripts/generate-docker-library.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+#
+# official-images tag file generator
+#
+# usage: ./generate-docker-library.sh > [official-images-folder]/library/tusd
+#
+
+cat <<-EOH
+# This file is generated via https://github.com/tus/tusd/blob/master/generate-docker-library.sh
+Maintainers: tus.io (@tus), Thomas A. Hirsch (@thirsch)
+GitRepo: https://github.com/tus/tusd.git
+EOH
+
+skipBeforeVersion="0.13.0"
+previousVersions=();
+
+function printVersion() {
+    version=( ${1//./ } )
+    majorMinor="${version[0]}.${version[1]}"
+
+    match=$(echo "${previousVersions[@]:0}" | grep -oE "\s?$majorMinor\s?$")
+    previousVersionCount=${#previousVersions[@]}
+
+    # add the majorMinor-Version only, if it is not present yet.
+    if [[ ! -z $match ]] ; then
+        versionString=$1
+    else
+        versionString="$1 $majorMinor"
+        previousVersions+=($majorMinor)
+    fi
+
+    # as the versions are sorted, the very first version gets latest.
+    if [[ ${previousVersionCount} -eq 0 ]]; then
+        versionString="$versionString, latest"
+    fi
+
+  cat <<-EOE
+
+Tags: $versionString
+GitCommit: $2
+	EOE
+}
+
+for version in `git tag -l --sort=-v:refname | grep "^[0-9.]\+$"`; do
+  commit=`git rev-parse ${version}`
+
+  # no official release before this version
+  if [[ ${version} = ${skipBeforeVersion} ]] ; then
+    exit 0
+  fi
+
+  printVersion "${version}" ${commit}
+done