Keystone Key Mgmt Service POC

[clevinson]

• [x] Register method (skipping OAuth part..)
  • creates group in group account with one key which is server signing key
  • returns Address
• [ ] create & send transaction
  • takes a list of messages from the user, creates a tx for the group account, and the server signs & submits it
  • returns TxResult (accepted for processing)
• [x] client being able to successfully call grpc Register method on the keystone server

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API should be:

• grpc server
• grpc-gateway for REST API