Rewrite of new thirdparty infrastructure

- Abandon old installer idea for new package which generates
  dependencies/recommendations at package build time.
- Use chdist(1) on Ubuntu to enable multiverse at package
  build time
- Add new build-dependencies on lsb-release and devscripts
- Drop cdbs build dependency and update debhelper one to
  7.0.50~, since we're using overrides

Additional changes:

- Syntax errors in the list files are now fatal.
- Slave dependencies are added correctly
- A missing distro-specific file is not an error
- Package is now arch-dependent, since there are some i386-only
  packages.