Debian packaging update

* Simplify things by creating a generic package that will generate the
  correct source file depending on their distribution.
  + Bump the package version number accordingly.
* Added the dailies sources lines (commented out) in the template directly.
* Added the multi-arch fix in the template directly - we only supply amd64
  packages anyway so make this default.
* Add an example on how to get the GPG key and use apt-key to add it to the
  system keyring.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #20