Optimize layers

[nigredo-tori]

Current Dockerfiles are split into separate steps.

1. Install build dependencies.
2. Build the engine.
3. Enable the engine.
4. Rebuild cURL.
5. Clean up.

The problem is that each of these steps produces a separate layer - and the first one can take a lot of space. To give you an example, rkix/openssl-gost:alpine image is around 80MB, but if you try to docker save it, you get a 300MB file! This is 200MB of useless data that everyone has to download and keep on their hard drive.

An obvious solution would be to move the whole process into a single shell script - this way we get a single layer with no dead weight.