Disable HTTP traffic on my entire computer
There is an application called SSL Enforcer (currently in beta) and works system-wide. It has 2 main modes of operation:


"Strict Mode" which forces https connections.
"Best Effort Mode" which will redirect to https when available.


I've tried it before, and found that when I set it to Strict Mode it broke some websites with mixed content. Here are the applications "Key Features" via its webpage:


  Works for all apps including browsers, plug-ins and any other Internet clients.
  
  No data leaks. Blocks unsecure connections on the system level starting from the very first request.
  
  Switches to secure connections (HTTPS) automatically if available.
  Flexible rules based on application name, target host and port.
  
  Does not use a tunnel or proxy server. Your traffic goes directly to the target with maximum speed.