Group access to private encrypted types

Enable group specific encryption/decryption:
1. a user creates a new group
2. the new group gets a new random key, which is encrypted by the user permanent password (and groups have one encrypted key per member encrypted by each individual member key)
A. A new user is added to the group by one current group member
B. The current members key is used to decrypt the group key, and the new members key is used to encrypt the key and store it for the new user in the group key list (<UUID user><String encrypted groupkey>)