title: Error validating token. Proxy not authorized in keystone. Keystone authentication
body: <p>I was trying to incorporate IDM (Docker) latest, and pep-proxy (git example running with node server).</p>
  
  <p>When I started pep-proxy, everything was working as intended. 
  I've got the following messages:</p>
  
  <ol>
  <li><p>INFO: Server - Starting PEP proxy in port 80. IdM authentication...</p></li>
  <li><p>Server - Success authenticating PEP proxy. Proxy Auth-token:  d9badf48-16fa-423d-884c-a3e155578791</p></li>
  </ol>
  
  <p>Now a problem happens. When I enter the wrong token I get this error.</p>
  
  <pre><code>ERROR: IDM-Client - Error validating token. 
  Proxy not authorized in keystone. Keystone authentication ... 
  ERROR: Server - Caught exception: 
  SyntaxError: Unexpected token u in JSON at position 0
  </code></pre>
  
  <p>As far as I understand I am expecting some return like invalid token, etc.. instead I get this error in pep-proxy and my curl command show->(52) Empty reply from server.</p>
  
  <p>My config.json of pep-proxy:</p>
  
  <pre><code>var config = {};
  
  // Used only if https is disabled
  config.pep_port = 80;
  
  // Set this var to undefined if you don't want the server to listen on  HTTPS
  config.https = {
    enabled: false,
    cert_file: 'cert/cert.crt',
    key_file: 'cert/key.key',
    port: 443
  };
  
  config.idm = {
    host: 'localhost',
    port: 3000,
    ssl: false
  }
  
  config.app = {
    host: 'www.google.es',
    port: '80',
    ssl: false // Use true if the app server listens in https
  }
  
  // Credentials obtained when registering PEP Proxy in app_id in Account Portal     
  config.pep = {
    app_id: 'xxxxxx',
    username: 'xxxxxx',
    password: 'xxxxxx',
    trusted_apps : []
  }
  
  // in seconds
  config.cache_time = 300;
  
  // if enabled PEP checks permissions with AuthZForce GE. 
  // only compatible with oauth2 tokens engine
  //
  // you can use custom policy checks by including programatic scripts 
  // in policies folder. An script template is included there
  config.azf = {
    enabled: true,
    protocol: 'http',
    host: 'localhost',
    port: 8080,
    custom_policy: undefined // use undefined to default policy checks (HTTP verb + path).
   };
  
   // list of paths that will not check authentication/authorization
   // example: ['/public/*', '/static/css/']
   config.public_paths = [];
  
   config.magic_key = 'undefined';
  
   module.exports = config;
  </code></pre>
  
  <p>IDM logs:</p>
  
  <pre><code>fiware-idm_1  | GET                                                
  /user?access_token=7cb25729577c2e01dc337314dcd912ec981dc49b 401 4.445 ms -  116
  
  fiware-idm_1  | Executing (default): SELECT email, 'user' as Source FROM  
  user WHERE email='pep_proxy_edf60435-7de7-4875-85a9-cf68b8838b8c'
  fiware-idm_1  |                  UNION ALL
  fiware-idm_1  |                  SELECT id, 'pep_proxy' as Source FROM    
  pep_proxy WHERE id='pep_proxy_edf60435-7de7-4875-85a9-cf68b8838b8c';
  fiware-idm_1  | Executing (default): SELECT `id`, `password`,    
  `oauth_client_id` FROM `pep_proxy` AS `PepProxy` WHERE `PepProxy`.`id` = 
  'pep_proxy_edf60435-7de7-4875-85a9-cf68b8838b8c';
  fiware-idm_1  | Executing (default): INSERT INTO `auth_token` 
  (`access_token`,`expires`,`valid`,`pep_proxy_id`) VALUES ('a0d54a6f- 
  8461-4000-bb80-5fb60193bcb4','2018-05-04 
  11:45:21',true,'pep_proxy_edf60435-7de7-4875-85a9-cf68b8838b8c');
  fiware-idm_1  | POST /v3/auth/tokens 201 13.733 ms - 74
  </code></pre>