aba953c3b6
This change set implements the "context path" discovery for the CalDav/CardDav endpoints. This basically implements the bootstrapping process as defined in RFC6764 section 6, point 2 and 3. What's missing in this implementation is the fallback that is described in point 3, subpoint 3, which says that if the context path discovered in the TXT RR is not reachable the .well-known URI should be used instead. I propose to implement this in a future iteration.
