Support additional request types for caldav

[haraldk]

Caldav uses, for example, REPORT instead of PUT. In line 5252 of jquery-1.4.2.js we have

xhr.send( type === "POST"

type === "PUT"

type === "DELETE" ? s.data : null )

It would be cool if this were configurable and would rather read something like

xhr.send( s.sendData[type] ? s.data : null )

where s.sendData is a map from request types to true or false.

[snover]

Duplicate of #6462.