Returns the license file for this builder.
        
        :return     <str>

def licenseFile(self):
        """
        Returns the license file for this builder.
        
        :return     <str>
        """
        if self._licenseFile:
            return self._licenseFile
        elif self._license:
            f = projex.resources.find('licenses/{0}.txt'.format(self.license()))
            return f
        else:
            return ''