Failing test for UTF-8 compatibility

    Failures:

      1) GreenCard::Vcard should not choke on utf8
         Failure/Error: vcard = GreenCard::Vcard.decode(vcard_text)
         Encoding::CompatibilityError:
           incompatible encoding regexp match (ASCII-8BIT regexp with UTF-8 string)
         # ./lib/greencard/vcard.rb:667:in `==='
         # ./lib/greencard/vcard.rb:667:in `decode'
         # ./spec/greencard/vcard_spec.rb:12:in `block (2 levels) in <top (required)>'

This is the first step towards fixing h2s/ppl#17. I have a few different ideas
in mind for fixes, mainly based on stuff I've seen in other repositories that
claim to fix this library's support for Ruby >= 1.9. But in the meantime, here's
some token amount of forwards movement on this issue at long last.
The first part of the h2s/greencard#1, this stops the first fatal error

The core problem remains, but with this tweak execution manages to struggle
along for an entire two further lines before dying of another
Encoding::Compatibility

    Failure/Error: vcard = GreenCard::Vcard.decode(vcard_text)
    Encoding::CompatibilityError:
      incompatible encoding regexp match (ASCII-8BIT regexp with UTF-8 string)
    # ./lib/greencard/vcard.rb:669:in `==='
    # ./lib/greencard/vcard.rb:669:in `decode'
    # ./spec/greencard/vcard_spec.rb:12:in `block (2 levels) in <top (required)>'

It's not much, but it's a start.
Screw it, I tried. This code doesn't even seem to be very important anyway.

One alternative approach I didn't see when I wrote h2s/greencard#1 was this:
https://github.com/qoobaa/vcard/commit/47b7e9d4be2c930548ae62681dae6a3827aafa5b
Merge branch 'utf8'