Better support for Deb packages

- Change the arch setting type to String to allow setting "amd64" for Deb packages.
- Added maintainer, uploaders & priority fields for Deb packages
- Fixed a bug with setPostUninstall which was calling preUninstall instead of postUnintall
- Added configurationFiles for Deb packages which will be written to conffiles, this can probably be done better by using the fileType property