Support RPM package

  * growl-for-linux.rpm
    binaries: gol
    plugins: ballon, fog, nico2
  * growl-for-linux-display-notify.rpm
    plugins: libnotify
  * growl-for-linux-subscribe-rhythmbox.rpm
    subscribes: rhythmbox

Signed-off-by: Kohei Takahashi <flast@flast.jp>