image_builder: add sudo for zip command

.travis.yml

@@ -23,7 +23,7 @@ before_deploy:
   - git config --local user.name "urpylka"
   - git config --local user.email "urpylka@gmail.com"
   - git tag "$(date +'%Y%m%d%H%M%S')-$(git log --format=%h -1)"
-  - cd ${BUILD_DIR} && zip ${IMAGE_NAME}.zip ${IMAGE_NAME}
+  - cd ${BUILD_DIR} && sudo zip ${IMAGE_NAME}.zip ${IMAGE_NAME}
 deploy:
   provider: releases
   api_key: ${GITHUB_OAUTH_TOKEN}