Improved import and export of vcards notably including encoding/decoding.

- Fixed bug created when I changed Node->types() previously.
- Added comments in the code which point to the RFC so its clear why we do
  those things.
- Rewrote Text::vCard::Node->as_string()
- Text::vCard::Addressbook->export() now uses Text::vCard->as_string()
- Wrote code to wrap utf8 encoded strings
- Fixed encoding issues with MIME::Base64 and MIME::QuotedPrint
- Created and updated many tests
- Added new pod explaining encoding and utf-8 stuff
- Unescape '\', ';', and ',' when reading a vcard file per the RFC.
- Mostly things worked in the past if you were reading vcards but were very
  problematic if you writing vcards.  This situation has been greatly improved.
- Fixed a problem writing vcards which caused output to look like 'N;=Batman'
  instead of 'N=Batman'
- Fixed a problem with writing ORG values where the output was a ',' but should
  have been a ';'.
- Possibly other things I forgot to mention.
Make all the vcf files have crlf line endings. Git was auto 'fixing' them.
Moar better POD
Merge pull request #12 from kablamo/import-export-encoding

Improves vcard import export has better encoding handling - THANK YOU!