Fixes #75, where @git-version@ was not replaced in the output path.

The problem was that I am using @git-version@ in other parts of the Box project. So as part of the build process _for_ Box, I am replacing that placeholder with the actual version number. So, when other people use this feature, it's searching for Box's current version number to replace.

src/lib/KevinGH/Box/Configuration.php

@@ -759,8 +759,8 @@ public function getOutputPath()
             $path = $base . 'default.phar';
         }
 
-        if (false !== strpos($path, '@git-version@')) {
-            $path = str_replace('@git-version@', $this->getGitVersion(), $path);
+        if (false !== strpos($path, '@' . 'git-version@')) {
+            $path = str_replace('@' . 'git-version@', $this->getGitVersion(), $path);
         }
 
         return $path;