Add development docker image

[aaahrens]

Is your feature request related to a problem? Please describe.

Right now the only image is multi staged into scratch, which means that it is unusable from a CI perspective, because both drone and gitlab use /bin/sh to run processes and grep outputs.

Describe the solution you'd like

Add a development docker image tag. ory/hydra-alpine:v1.0. Or something similar. /shrug

Describe alternatives you've considered

Right now we have to build our custom images that replicate on hydra's dockerhub. This just removed a step and guarentees that the images are mirrored right.

[aeneasr]

Ok, those are valid reasons and we'll add a vX.Y.Z-alpine image for these use cases to Docker Hub