Apply a linter if the scope name starts with any of the linter's syntaxes 

I have a package that modifies the scope name for certain python files to be `source.python.django.models` or `source.python.django.forms`.  

Instead of listing all possible scope names in the linter's syntax, I believe it would be better to check if the scopeName starts with the given syntax, in this case `source.python`.

Also created and published [linter-pep8](https://atom.io/packages/linter-pep8) and [linter-pyflakes](https://atom.io/packages/linter-pyflakes).  If you want to bring these under the `AtomLinter` umbrella, let me know.