Add docker

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

update-submodules.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+paths=$(git config --file .gitmodules --name-only --get-regexp path | while read -r line; do
+  path=$(git config --file .gitmodules --get "$line")
+  url=$(git config --file .gitmodules --get "${line%.*}.url")
+  if [[ $url == *"karaolidis"* ]]; then
+    echo "$path"
+  fi
+done)
+
+for path in $paths; do
+  echo "Processing submodule: $path"
+
+  cd "$path"
+  git checkout master
+  git fetch upstream
+  git merge upstream/master
+
+  branches=$(git for-each-ref --format='%(refname:short)' refs/heads/ | grep -v '^master$')
+  for branch in $branches; do
+    git checkout "$branch"
+    git rebase master
+  done
+
+  git checkout master
+  git push origin --all --force-with-lease
+  git push origin --tags --force-with-lease
+
+  cd - > /dev/null
+done
+
+echo "All submodules updated successfully."