Release version 1.0.0

This release adds a workaround that allows the usage of the efficient synchronization methods (sync-collection and multiget reports) with sabre/dav, which otherwise may fail because of an incompatibility between sabre/dav and curl. An example for an affected environment is Baïkal 0.7.2 with digest authentication.

Otherwise, the library has been working stable for the past couple of months and been in deployment by rcmcarddav v4 users, so I decided to release it as 1.0.0 (and hope the added workaround doesn't break things, but the tests still run fine).