Add compatibility checks

[gsiv]

For the management service to work, the following components must be compatible:

• the openslides binary
• the management service
• templates
• configuration files

As far as I can tell, there are currently no compatibility checks in place. Instead, users must rely on the vague error messages to find the flaws with their setup.

Wouldn't it be a good idea to add version identifiers and checks to the management tool? For example, breaking changes such as #172 could be detected by openslides and pointed out with much more helpful info, e.g., "This v1 template is incompatible with openslides v2". Similarly, when communicating with the management service, it would be nice to read, e.g., "Can not create user: incompatible management service version".

[normanjaeckel]

Does someone have an idea how to solve this easily? At the moment I don't have because the manage tool changes from time to time and we do not have a stable version until now.

[normanjaeckel]

We introduced a version number with #208 but maybe we can extend it also to the tool itself.