adds ability to ignore ids based on specified patterns

I wanted to be able to easily have commoner ignore test files and not try to resolve them, I couldn't figure it out easily so I just added support to filter the ids after globing them. If there is a cleaner solution or this is already solved in some other way I'd be happy to just improve documentation or examples instead

Now I can just do this in my custom config to have it ignore test files
```
require('commoner')
  .ignorePattern(/.*\/__tests__\/.*/)
  .resolve(function(id) {
      return this.readModuleP(id);
  }).process(function(id, source) {
    return source;
  });
```