Updates phpdoc required version to 2.x stable.

Author: beporter

composer.json

@@ -11,7 +11,7 @@
     "require": {
         "php": ">=5.3.0",
         "phpunit/phpunit": "3.7.*",
-        "phpdocumentor/phpdocumentor": "2.*@beta",
+        "phpdocumentor/phpdocumentor": "2.*",
         "squizlabs/php_codesniffer": "1.*",
         "loadsys/loadsys_codesniffer": "0.*"
     },