Validation of .universum.py

[i-keliukh]

The project steps defined in the config file (.universum.py by default) must be validated before use. Specifically, each field of each step must be checked for proper runtime type, valid values, etc.

The check should be implemented in configuration_support module and reused in the launcher module. This would allow end user to perform the sanity check on their side even before it is passed to the launcher. It is also a good place, because it already contains documentation and type declarations for keys.

As a phase two, the configs file must be processed in a separate interpreter instance, spawned with subprocess. This will isolate main universum instance from the programming errors within the config file.