Fix to JHttpTransportSocket

Fixes 2 issues ocuring during Extension updates:
- first, the `JHttpFactory::getHttpTransports` method may return transports in random order, so the diver autoselection may picks `JHttpTransportSocket` instead of `Curl`.
- support of `follow_location` to `JHttpTransportSocket` so it may handle 301-type responses.

Related Issue tracker:
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32468