Is there a way to use Tor system-wide?
All the above steps will make you crazy. I am going to share with you what I have chosen to and works perfectly.
Install torsocks by going to Ubuntu Software Center and typing "tor" and select additional packages.
After installation, go to System Settings... → Network → Network proxy and enter these settings:
127.0.0.1
and port9050
into SOCKS section.Apply and restart.
In all your browsers and apps choose to "Use System Proxy Settings".
You may want to try these instructions on using Tor as a transparent proxy, as provided by the TOR-project itself.