fixed config typo (#42)

Author: wachterjohannes

src/Resources/config/executor/separate.xml

@@ -11,7 +11,7 @@
 
         <service id="task.executor.separate.process_factory" class="Task\TaskBundle\Executor\ExecutionProcessFactory">
             <argument type="string">%task.executor.console_path%</argument>
-            <argument type="string">%kernel.environment%%</argument>
+            <argument type="string">%kernel.environment%</argument>
         </service>
     </services>
 </container>