Extract text from pdfs using the pdftotext command line utility.

def extract_pdftotext(self, filename, **kwargs):
        """Extract text from pdfs using the pdftotext command line utility."""
        if 'layout' in kwargs:
            args = ['pdftotext', '-layout', filename, '-']
        else:
            args = ['pdftotext', filename, '-']
        stdout, _ = self.run(args)
        return stdout