Update __init__.py

I use next regex^
regex = re.compile(
        r'(?=^.{1,254}$)(^(((?!-)[a-zA-Z0-9-]{1,63}(?<!-))|((?!-)[a-zA-Z0-9-]{1,63}(?<!-)‌​\.)+[a-zA-Z]{2,63})$)', re.IGNORECASE)

In case of re.match failure I get:
File "venv/lib/python2.7/site-packages/trafaret/__init__.py", line 591, in check_and_return
    value, self._raw_regex)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 79: ordinal not in range(128)

My fix excludes this situation.