Allow retrieval of descriptive and/or legally relevant information about the APY server

What I have in mind is something like this:
```
$ curl 'http://fancytranslations.example:2737/about?lang=spa|fra'

{"responseStatus": 200, "responseData": {
"serviceName": "Fancy-Translate",
"serviceDescription": "One-line description, preferably in Spanish or French",
"serviceWebsiteURL": "http://www.fancytranslations.example/spa/index.html",
"legalNoticeURL": "http://www.fancytranslations.example/spa/legal.html",
"privacyStatementURL": "http://www.fancytranslations.example/spa/privacy.html"
}, "responseDetails": null}
```
A web front-end could then put this information in its privacy statement.