Release 0.9.0

This is a feature release. Main features are:

• support for the slashing protection interchange format, and related commands to import and export the data
• support for the eth2-signer-api multisign API for attestations

Changelog:

• Use fastssz for calculating hash tree roots
• Add endpoint to sign multiple attestations in a single call
• Provide hard-coded daemon for testing (see testing directory)
• Add commands to import and export slashing protection data
• Provide additional trace logging for distributed key generation
• Enforce requirement that peer names cannot be the same
• Exit early in distributed key generation if execution fails
• Allow process.generation-passphrase to be a Majordomo URL
• Add comments to rules functions
• Log location of wallet stores on startup