Fix dependency

composer.json

@@ -25,6 +25,7 @@
     },
     "require": {
         "composer-plugin-api": "^1.0.0",
+        "cypresslab/gitelephant": "~1.0",
         "php": ">=5.4.5"
     },
     "autoload": {
@@ -37,7 +38,6 @@
     },
     "require-dev": {
         "composer/composer": "dev-master",
-        "cypresslab/gitelephant": "~1.0",
         "phpunit/phpunit": "^4.4.0"
     }
 }