Add Dockerfile to create base layer image
Add Dockerfile to create base layer image

Add Dockerfile to create a base layer image containing only the Spruce
binary build from source. The version is based on Git describe.

geofffranks/spruce,HeavyWombat/spruce,HeavyWombat/spruce,geofffranks/spruce,geofffranks/spruce,HeavyWombat/spruce