Import all *.py files in specified directory.

def import_pyfiles(path):
    """
    Import all *.py files in specified directory.
    """
    n = 0
    for pyfile in glob.glob(os.path.join(path, '*.py')):
        m = import_file(pyfile)
        IMPORTED_BUILD_SOURCES.append(m)
        n += 1
    return n