Updated the version parser regular expression

Author: javiereguiluz

src/Symfony/Installer/NewCommand.php

@@ -111,8 +111,8 @@ protected function checkSymfonyVersionIsInstallable()
         }
 
         // validate semver syntax
-        if (!preg_match('/^2\.\d(?:\.\d{1,2})?(?:-(?:dev|BETA\d*|RC\d*))?$/i', $this->version)) {
-            throw new \RuntimeException('The Symfony version should be 2.N or 2.N.M, where N = 0..9 and M = 0..99. The special "-dev" "-BETA" and "-RC" suffixes are also supported.');
+        if (!preg_match('/^2\.\d(?:\.\d{1,2})?|2\.\d(?:-(?:dev|BETA\d*|RC\d*))$/i', $this->version)) {
+            throw new \RuntimeException('The Symfony version must be 2.N or 2.N.M (where N and M are positive integers). The special "-dev", "-BETA" and "-RC" versions are also supported.');
         }
 
         if (preg_match('/^2\.\d$/', $this->version)) {