tools: Fix running check-openapi locally.

tools/check-openapi

@@ -1,3 +1,5 @@
+#!/usr/bin/env node
+
 var SwaggerParser = require('swagger-parser'),
     _             = require('underscore');
 

tools/linter_lib/exclude.py

@@ -10,6 +10,7 @@ EXCLUDED_FILES = [
     # newlines; there's nothing other than trailing newlines we'd be
     # checking for in these anyway.
     "locale",
+    "tools/check-openapi",
 ]
 
 PUPPET_CHECK_RULES_TO_EXCLUDE = [