Remove direct Strider-in-Docker support

Instead now we redirect to the separate repository that I've transferred over: https://github.com/Strider-CD/docker-strider

closes #647

Hopefully issues can accumulate there instead of Strider. Also, Docker is for advanced users... so this image is advanced (it does not work without the user knowing how to link a MongoDB image or utilize the env var passing feature to provide Mongolab or some other public cloud mongo service). I suppose in contrast, If we want an "all-in-one" or simple image, we can take the files I removed in this PR and make a new repo with it, however the docker-strider one is something that people would use in the real-world whereas the all-in-one is like a toy that a novice would use just to say "look ma I'm running strider in Docker!"