add libjpeg-dev, zlib1g-dev, libpng-dev
add libjpeg-dev, zlib1g-dev, libpng-dev

Add the noted packages to pre-req list for Pillow

edwinsteele/biblebox-pi,edwinsteele/biblebox-pi,edwinsteele/biblebox-pi,edwinsteele/biblebox-pi,edwinsteele/biblebox-pi,edwinsteele/biblebox-pi