Read and parse files from a directory,
        return a dictionary of path => post

def get_files(self):
        """
        Read and parse files from a directory,
        return a dictionary of path => post
        """
        files = {}
        for filename in os.listdir(self.source):
            path = os.path.join(self.source, filename)
            files[filename] = frontmatter.load(path, 
                filename=filename, 
                slug=os.path.splitext(filename)[0])

        return files