Debian package fixes

1. Use --with python2
2. Add build dependency on Python.
3. wrap-and-sort control, copyright and install files.
4. Fix installation location for goopg-chrome.install
Oh,

I know .. this is odd, but the right place where to put that file is exactly "/etc/opt"

For more info, see:
 * the original doc: https://developer.chrome.com/extensions/messaging#native-messaging
 * this bug-comment which has a summary about directories in chrome and chromium: https://code.google.com/p/chromium/issues/detail?id=237873#c35

Can you please revert this change?