Make User agent string for external fetches configureable.
I tried to fetch "Upcomming Events" from Facebook as external calendar and got nothing. A manual curl on the commandline was always successful. So I started debugging and found out, that all davical gets is:
HTTP/1.1 302 Found
Location: https://www.facebook.com/unsupportedbrowser
access-control-allow-method: OPTIONS
Vary: Origin
Access-Control-Expose-Headers: X-FB-Debug, X-Loader-Length
Access-Control-Allow-Origin: https://www.facebook.com
Access-Control-Allow-Credentials: true
Content-Type: text/html
X-FB-Debug: xxx
Date: Wed, 12 Apr 2017 01:09:56 GMT
Connection: keep-alive
Content-Length: 0
So I need to change the UA-String for this usecase.