In #793, we rewrote sendHttpRequest because allow_url_fopen is often disabled. It seems fsockopen is a similar casualty of overzealous sysadmins.
In [1391], fixes #925, refs #793 - provide curl and stream methods (as originally proposed by Uli)
Order of preference: curl (6s), stream (10s), socket (13s) to d/l latest.zip
Add Piwik::getTransportMethod() and add to Installation system check