Fix for non-ASCII Unicode tasknames.

Without this patch, when a task has non-ASCII characters in the task list, you get this error:

Traceback (most recent call last):
  File "/bin/wunderlist", line 9, in <module>
    load_entry_point('wunderpy==0.2.1', 'console_scripts', 'wunderlist')()
  File "/usr/lib/python2.7/site-packages/wunderpy-0.2.1-py2.7.egg/wunderpy/cli/main.py", line 135, in main
    cli.overview()
  File "/usr/lib/python2.7/site-packages/wunderpy-0.2.1-py2.7.egg/wunderpy/cli/main.py", line 57, in overview
    pretty_print_task(task_title, info)
  File "/usr/lib/python2.7/site-packages/wunderpy-0.2.1-py2.7.egg/wunderpy/cli/main.py", line 90, in pretty_print_task
    line = "[{}] {} {}".format(is_completed.encode("utf-8"), title, use_star)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 1: ordinal not in range(128)