Fixed Python3 error.

When running suddendeath on Python 3, following errors are occured.

    $ suddendeath
    Traceback (most recent call last):
      File "/Users/likr/local/python32/bin/suddendeath", line 9, in <module>
        load_entry_point('suddendeath==0.2.0', 'console_scripts', 'suddendeath')()
      File "/Users/likr/local/python32/lib/python3.2/site-packages/suddendeath/__init__.py", line 46, in main
        print((suddendeathmessage(message)))
      File "/Users/likr/local/python32/lib/python3.2/site-packages/suddendeath/__init__.py", line 30, in suddendeathmessage
        header = "＿" + "人"*header_chars + "＿"
    TypeError: can't multiply sequence by non-int of type 'float'
    $ suddendeath ぱいそん
    Traceback (most recent call last):
      File "/Users/likr/local/python32/bin/suddendeath", line 9, in <module>
    load_entry_point('suddendeath==0.2.0', 'console_scripts', 'suddendeath')()
      File "/Users/likr/local/python32/lib/python3.2/site-packages/suddendeath/__init__.py", line 44, in main
        message = sys.argv[1].decode("utf-8")
    AttributeError: 'str' object has no attribute 'decode'

I fixed it.