Handle non-ASCII encoding

[l0b0]

UTF-8 characters should not be detected as invalid text.

[citrin]

Quoted-printable encoding is not allowed (obsolete) in vCard 3.0 (RFC 2426).
QP can be used only in vCard 2.1

[citrin]

But non-ASCII charset encodings indeed should be supported.
RFC 2426 explicitly allow to use 8-bit strings. Because CHARSET parameter was removed from vCard 3.0 (compare to 2.1) and file contains no information about text charset you can assume that file uses utf-8.

But vcard tool can't parse utf-8 files. Error is:

... skipped ...
    property_.values = get_vcard_property_values(values_string)
  File "/home/citrin/.local/lib/python2.7/site-packages/vcard/vcard_validator.py", line 295, in get_vcard_property_values
    values.append(get_vcard_property_sub_values(sub))
  File "/home/citrin/.local/lib/python2.7/site-packages/vcard/vcard_validator.py", line 333, in get_vcard_property_sub_values
    raise VCardValueError('{0}: {1}'.format(NOTE_INVALID_SUB_VALUE, sub_value), {})
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-5: ordinal not in range(128)

It seems to be vcard first converts input text to python internal form (from raw octets to Unicode characters) then uses regex based on grammar from RFC2426 (NON-ASCII = %x80-FF). But it is wrong - %x80-FF should be applied to octets, not Unicode characters. Of course Unicode code points can be grater than 0xFF.

Test vCard in utf-8 can be found here: http://www.citrin.ru/tmp/minimal.vcf