updating expressjs method from 'host' to 'hostname' as the former is deprecated


Fixes expressjs deprecated method:

```
Mean app started on port 3000 (development)

express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:105
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:136
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:220
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:251
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:277
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:479
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:510
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:594
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:625
express deprecated req.host: Use req.hostname instead eval at <anonymous> (/home/superman/websites/lirantal.mean/node_modules/swig/lib/swig.js:483:11), <anonymous>:28:651
```