Wait for sidebar to ack setTool before applying

Without this change, clicking highlight mode and then dismissing the
authentication without logging in will make it so that one must click
it twice to trigger the behavior again.

h/js/guest.coffee

@@ -210,7 +210,7 @@ class Annotator.Guest extends Annotator
     )
 
     .bind('setTool', (ctx, name) =>
-      this.setTool name
+      @tool = name
       this.publish 'setTool', name
     )
 
@@ -400,7 +400,6 @@ class Annotator.Guest extends Annotator
     @noBack = false
 
   setTool: (name) ->
-    @tool = name
     @panel?.notify
       method: 'setTool'
       params: name