Fixed f-d up month logic

I'm not sure why this had Chronic parsing "last February".  Just figure
out the first day of this month instead.
Version 1.8.6 - Ruby 2.0 compatibility

Getopt Declare uses a \255 byte for internal escaping which doesn't play
well with Ruby 2.0.  Use the ascii group sperator "\29" instead which
plays better with unicode.

Also vendor getopt since it doesn't seem to be maintained any longer.

Resolves #57