Restructure the code as configurator + validator

[mjuric]

The current ./configure script (unnecessarily) mixes two things:

• Generating the Helm/shell configuration
• Validating and describing it in human-readable terms (e.g., printing out a summary of what will be created, together with the cost, checking that Docker images exist, etc.)

These two should be split up (e.g. ./configure and ./validate), where ./validate would work from generated files. This would allow validation to be run on any Helm values.yaml setup, or even be run after the ./configure output has been heavily customized by the user.

This would probably require rewriting the validation stage in Python (for proper reading of YAMLs).