cleanup warehouse settings (#43)

launch/warehouse_settings.launch.xml

 <launch>
-  <!-- Set the parameters for the warehouse and run the mongodb server. -->
+  <!-- Set the parameters for the warehouse. -->
 
   <!-- The default DB port for moveit (not default MongoDB port to avoid potential conflicts) -->  
   <arg name="moveit_warehouse_port" default="33829" /> 
@@ -10,7 +10,5 @@
   <!-- Set parameters for the warehouse -->
   <param name="warehouse_port" value="$(arg moveit_warehouse_port)"/>
   <param name="warehouse_host" value="$(arg moveit_warehouse_host)"/>
-  <param name="warehouse_exec" value="mongod" />
   <param name="warehouse_plugin" value="warehouse_ros_mongo::MongoDatabaseConnection" />
-
 </launch>