• Add automatic determination of the KV secret engine version (#12)
  The version of the used KV secret engine is now determined by the operator. It is not necessary to specify the KV secret engine version in the CR field spec.secretEngine. We keep this field, so we can use it later for other secret engine implementations. This also fixes the bug mentioned in #11.
• Add default address for Vault (#13)
  The default value of the Vault address in the Helm chart points to http://vault:8200 now.