Add support for http_proxy

[rayterrill]

Suggested addition to collect.js:

// ADDED PROXY CONFIGURATION
if (process.env.http_proxy) {
console.log('INFO: Setting proxy to [' + process.env.http_proxy + '] from the environment variable http_proxy...');
var proxy = require('proxy-agent');
AWS.config.update({
httpOptions: { agent: proxy(process.env.http_proxy) }
});
}