Changed the semaphore and general sign AR tags to coincide with the rulebook.

launch/spawn_semaphore.launch

@@ -2,7 +2,7 @@
 <launch>
   <arg name="name"  default="semaphore"/>
   <arg name="model" default="semaphore"/>
-  <arg name="tag"   default="alvar0_neg_1"/>
+  <arg name="tag"   default="alvar1_neg_1"/>
   <arg name="initial_state"  default="False"/>
   <arg name="x"     default="0.5"/>
   <arg name="y"     default="-0.5"/>

launch/spawn_sign.launch

@@ -2,7 +2,7 @@
 <launch>
   <arg name="name"  default="stop"/>
   <arg name="model" default="sign"/>
-  <arg name="tag"   default="alvar1_neg_1"/>
+  <arg name="tag"   default="alvar0_neg_1"/>
   <arg name="type"  default="stop"/>
   <arg name="x"     default="0.5"/>
   <arg name="y"     default="-0.5"/>