add --all-tags to pull & pull latest by default

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
add a little documentation for docker pull

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
docker build: pull just latest if tag uspecified

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Allows installation on Linux Mint Debian Edition

Otherwise platform won't be detected

Signed-off-by: Tomasz Lipinski <me@tlipinski.net>
Merge pull request #7891 from tlipinski/master

Allows installation on Linux Mint Debian Edition
Merge pull request #7759 from unclejack/pull_latest_by_default

make docker pull only the latest tag by default