Add Docker builds for arm/v6, arm/v7 and arm64. (#546)
Add Docker builds for arm/v6, arm/v7 and arm64. (#546)

Signed-off-by: Krasi Georgiev <e7a6a3244daab0176ed092eaae0bd186fa4e17ac@users.noreply.github.com>
brocaar/loraserver,brocaar/loraserver