Rename contrib files where appropriate
Replace bitcoin with dogecoin in debian files

- Primarily bitcoin Bitcoin and BITCOIN
- A few fixes (e.g. bitcoin.org -> dogecoin.com)
- Debian building not actually tested, I'm doing this to prep for RPMs
Back out pixmap path changes

dogecoin doesn't have custom linux icons (yet)
Merge pull request #156 from vitaminmoo/contrib-to-dogecoin

Contrib to dogecoin