Implement basic range verificator.
Implement disk volume class.
Add mock to requirements.
Merge pull request #3 from serathius/system_backend

System backend
Refactor. Move.
Refactor.
Add value extractors.
Add System Verificators.
Merge pull request #4 from serathius/system_verificator

System verificator
Implement basic range verificator.
Refactor. Move.
Refactor.
Implement disc volume class.
Add file system backend.
Refactor.
Add description to value extractor.
Refactor.
Add specialized exceptions for RangeVerificator boundries.
Add Logger.
Add verification suit.