Add a list of PHP extensions required to the composer.json.

composer.json

@@ -27,6 +27,14 @@
     },
     "require": {
         "php": ">=5.3",
+		"ext-SPL": "*",
+		"ext-zlib": "*",
+		"ext-pcre": "*",
+		"ext-openssl": "*",
+		"ext-dom": "*",
+		"ext-date": "*",
+		"ext-hash": "*",
+		"ext-json": "*",
         "simplesamlphp/saml2": "dev-master#00e38f85b417be1e10a2d738dd2f5ea82edb472c as 2.2",
         "robrichards/xmlseclibs": "~2.0",
         "whitehat101/apr1-md5": "~1.0",