Apt-get: Cannot initiate the connection to 8080:80 (0.0.31.144).

I've seen this problem sometimes cropping up! One of the reasons this problem can occur is when your http_proxy variable is not set properly!
The $http_proxy variable in your terminal overrides the http::proxy variable in /etc/apt/conf file and the connection is not established if the http_proxy variable in the terminal is set to [proxy]:[port] instead of http://[proxy]:[port]. To check this out do the following:

1. Type: echo $http_proxy in the terminal
2. If it is something like this: 10.1.1.30:8080, then type: http_proxy="http://10.1.1.30:8080" . (we're just adding the 'http://' before the content of the variable)

If the problem was because of the overriding variables, it'd be solved by now .. try typing sudo apt-get update and see if it works.