Load the given config file.

            @param filename: the filename including the path to load.

def load(self, filename):
        ''' Load the given config file.

            @param filename: the filename including the path to load.
        '''
        if not os.path.exists(filename):
            #print 'Could not load config file [%s]' % (filename)
            raise AppConfigValueException('Could not load config file {0}'.
                    format(filename))
        cfl = open(filename, 'r')
        if PY2:
            self.readfp(cfl)
        else:
            self.read_file(cfl)
        cfl.close()