Fix bug in reading and persisting keystore data

[austinabell]

Summary of changes
Changes introduced in this pull request:

• After Add Persistent KeyStore #604 file was created on initializing a keystore, but was never written. When the file was attempted to be read, if the bytes were invalid, the node would error before starting.
  • I was going to make the file read recoverable, but in the case of a file not being fully written and has keys that are wanted, figured overwriting shouldn't be assumed

Reference issue to close (if applicable)

Closes

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