Update APIv2

As already reported, the upgrade to a new API version (APIv2) has taken place. In the course of this upgrade, some temporary inconveniences occurred. These include, e.g., the creation of resources or restrictions in the e-mail verification. The majority of these issues are already successfully resolved and we continue to work on making the functions in Coscine and the process as smooth as possible. Thank you for your understanding and patience as we work through these improvements.