Require PHP 5.4.0 as a minimum
Clean up annoying 5.3 $that = $this
Remove horribly annoying 5.3 StreamInterface extends bug

This was needed because you could not implement two interfaces with a
shared method. In 5.3.8+ it is fixed, so the hack is no longer needed in
5.4.0+.
Add 5.4 to CHANGELOG
Remove $that craziness from SecureConnector