tells Python to treat the string as a unicode string (issue with foreign language)

which fixed this kind of issue:
File "migrate.py", line 219, in <module>
    print "Created: {0} with {1} comments".format(issue['title'], comment_count)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 1: ordinal not in range(128)