Code cleanup

Cleanup (#156)

* Refactor quorum service

* Refactor user index
 service

* Renamed main file in the rpc server from index to server; Removed index file from dashcore; removed quorums dir from services

* Rename api folder to externalApis for clarity - it may be confused with the api provided by dapi; rename fixtures to mocks in tests, as they are mocks, not fixtures

* Moved all unit test to unit dir; Removed object-hash package and added cbor

* Bump version

* Add more verbose log messages to DAPI bootstrap

* Fix eslint warnings

* Remove username indexer spam to logs

* Add safeUpdateUsernameIndex function to username index

* Bump minor version

* Bump patch version

* Improve error handling

* Fix error handler tests

* Add dash rpc error handling to the error handler