Support building and pushing multiarch images

[tobybellwood]

This task could support pushing the built database image as multiarch into the target repository

[AlexSkrypnyk]

https://github.com/drevops/mariadb-drupal-data/blob/bbb90b494b16aecef2ba43869671f9e7e2814047/.circleci/config.yml#L25

[tobybellwood]

closed properly in #17

[tobybellwood]

wrong issue oops!