sudo wget http://curl.haxx.se/ca/cacert.pem -O /usr/lib/ssl/certs/cacert.pem

Ugh, I don't get it. It's not working. On my local server its working like a charm, but on my droplet no. Do you think its related to something on curl?
My code is this one, it returns nothing on $response:

require_once('lib/TwitterAPIExchange.php');
include "config.php";

$url = 'https://api.twitter.com/1.1/search/tweets.json';
$getfield = '?q=porra&result_type=recent&count=100';
$requestMethod = 'GET';
$twitter = new TwitterAPIExchange($settings);

$response = $twitter->setGetfield($getfield)
->buildOauth($url, $requestMethod)
->performRequest();

@diego: What is the actual error that you're seeing? Why do you think the problem is with the certificate?