Added SSL verification to PHPHttpRequest.

PHP's stream context options support SSL server verification as well a CN matching and provision of
CA info.
Added options to the stream context so that the $sslVerifyHost, $sslVerifyCert, and $caInfo
parameters now work in non-CURL environments.

Change-Id: Iab2bda1ebcf20b625b019c91ae6352b5405dcc01
Merge "Added SSL verification to PHPHttpRequest."