Email verification

@tdeekens ugly code is ready for review!

One needs to run emailverification.sql to change the database and change the config.json.

To send email from my local host I had to change php.ini to have this:
sendmail_path = /usr/sbin/sendmail -t -i -f  info@patat.com'

Then, in my config.json I have a different link under "links":
```json
"links": {
            "emailVerification": "<a href=\"http:\/\/localhost:8888\/lmvc-patat\/registration\/finish\/{usernamehash}\/{email}\/{randomkey}\">link</a> "
        }
```