Python3 config and plugins

[TomFaulkner]

• A bit more refactoring
• setup.py and newsctl executable. (This invalidates the old python news.py method.)
• dos2unix to convert all filenames to valid Linux files without breaking imports
• Removed warning and updated readme
• Plugin system so it is easier to add a news source, see plugin_registration for example of adding sites
• config.yaml is now read from and saved to a more reasonable location depending on operating system
• configuration is handled better and config.yaml is created automatically if it doesn't exist