Vagrant inventory: exit 0 on success

Current code has sys.exit(1) at the end of the codepath for the
options --help, --list and --host. These are not error conditions
so should be returning 0 for success, not 1 which is EPERM i.e.
"Operation not permitted". Newer Vagrant versions examine the exit
codes from subprocesses and interpret this as a failure.

plugins/inventory/vagrant.py

@@ -107,7 +107,7 @@ if options.list:
         hosts['vagrant'].append(data['HostName'])
 
     print json.dumps(hosts)
-    sys.exit(1)
+    sys.exit(0)
 
 # Get out the host details
 #------------------------------
@@ -122,11 +122,11 @@ elif options.host:
         result['ansible_ssh_port'] = result['Port']
 
     print json.dumps(result)
-    sys.exit(1)
+    sys.exit(0)
 
 
 # Print out help
 #------------------------------
 else:
     parser.print_help()
-    sys.exit(1)
+    sys.exit(0)