#15: _parse_ean() is now working. Added _match_table() function.
#15, #11: Added _parse_ean() test.
#4: Requirement in setup updated.
#15: _match_table() removed. Added _parse_from_table(). _parse_ean() done.
utils.py: Added must_contain().
#15: Added implementation of _parse_date(), _parse_format().
#15, #11: Added tests of _parse_date(), _parse_format().