Handle PROPFIND requests without a body

[emersion]

trafficstars

handlePropfind errors out if a PROPFIND request is sent without a body, I think. We should parse that as an allprop request:

A client may choose not to submit a request body. An empty PROPFIND request body MUST be treated as if it were an 'allprop' request.

https://www.rfc-editor.org/rfc/rfc4918.html#section-9.1