Implemented configuration frame work

Added reading and writing machinery's configuration file.
The file machinery_config.rb contains the default values
used when no configuration file is present.

This is a very indirect way of specifying the config file. In the spirit of the declaration of entries it would be nicer to do it in a more DSL like way. E.g. we could define a `default_config_file("path_to_config_file")` method to be called in the `define_entries` method.