Changed name of terrain model to prevent conflict (space-ros#46)

Signed-off-by: Jasmeet Singh <[email protected]>

Author: jasmeet0915

mars_rover/worlds/mars_curiosity.world

@@ -1,8 +1,5 @@
 <?xml version="1.0" ?>
 <sdf version="1.11">
-  <world name="default">
-<?xml version="1.0" ?>
-<sdf version="1.6">
   <world name="default">
     <physics name="1ms" type="ignored">
       <max_step_size>0.001</max_step_size>
@@ -247,7 +244,7 @@
 
   <include>
     <uri>/home/spaceros-user/demos_ws/install/simulation/share/simulation/models/curiosity_path</uri>
-    <name>curiosity_path</name>
+    <name>mars_terrain</name>
     <pose>0 0 0 0 0 0</pose>
   </include>