test(cli): fix tests for running in .travis

test/node/cli.js

@@ -1,10 +1,11 @@
-var execSync = require('child_process').execSync;
+var execSync = require('child_process').execSync,
+    cmd = 'node bin/showdown.js';
 
 describe('showdown cli', function () {
   'use strict';
 
   it('basic stdin stdout', function () {
-    var otp = execSync('showdown makehtml', {
+    var otp = execSync(cmd + ' makehtml', {
       encoding: 'utf8',
       input: '**foo**'
     });