Other fixes:
* Fix bit rot in the `make prater-dev-deposit` target.
* Correct content-type in the responses of the Nimbus signing node
* Invalid JSON payload was being sent in the web3signer requests
* Initial commit.
* Fix current test suite.
* Fix keymanager api test.
* Fix wss_sim.
* Add more keystore_management tests.
* Recover deleted isEmptyDir().
* Add `HttpHostUri` distinct type.
Move keymanager calls away from rest_beacon_calls to rest_keymanager_calls.
Add REST serialization of RemoteKeystore and Keystore object.
Add tests for Remote Keystore management API.
Add tests for Keystore management API (Add keystore).
Fix serialzation issues.
* Fix test to use HttpHostUri instead of Uri.
* Add links to specification in comments.
* Remove debugging echoes.
zah
Eugene Kabanov