Composer: update phpunit version to work with PHP 5.3/4

Author: terrafrost

composer.json

@@ -25,7 +25,7 @@
         "phpseclib/phpseclib": "~2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.*|5.*"
+        "phpunit/phpunit": "~4.0"
     },
     "suggest": {
         "ext-openssl": "Will enable faster cryptographic operations"