PHP 5.6 CA file/path

This is added for the new changes to PHP 5.6 (only affects version >= 5.6 but may be backported to PHP 5.5 later) for TLS Peer verification:

"Global CA defaults may be specified via new openssl.cafile and openssl.capath php.ini directives" (https://wiki.php.net/rfc/tls-peer-verification, https://wiki.php.net/rfc/improved-tls-defaults)

Slightly different from a straight php.ini configuration setting though as, if php.ini does not have a setting specified, it defaults to the settings specified in the installed version of openssl.

Tests added as well (and small fixes to other tests).

Be aware that PHP is still in 5.6.0-alpha3 release at the moment so this functionality may change before final release.