message: [safety-rules] Use crypto-storage for testing
  Before crypto-storage didn't have an import api. Now it does, but just
  for testing.
  Closes:
  Approved by: joshlind
diff: @@ -41,7 +41,7 @@ impl PersistentSafetyStorage {
  private_key: Ed25519PrivateKey,
  waypoint: Waypoint,
  ) -> Result<()> {
  - internal_store.set(CONSENSUS_KEY, Value::Ed25519PrivateKey(private_key))?;
  + internal_store.import_private_key(CONSENSUS_KEY, private_key)?;
  internal_store.set(EPOCH, Value::U64(1))?;
  internal_store.set(LAST_VOTED_ROUND, Value::U64(0))?;
  internal_store.set(PREFERRED_ROUND, Value::U64(0))?;
  @@ -56,16 +56,9 @@ impl PersistentSafetyStorage {
  }
  pub fn consensus_key(&self) -> Result<Ed25519PrivateKey> {
  - Ok(self
  - .internal_store
  - .get(CONSENSUS_KEY)
  - .and_then(|r| r.value.ed25519_private_key())?)
  - }
  -
  - pub fn set_consensus_key(&mut self, consensus_key: Ed25519PrivateKey) -> Result<()> {
  self.internal_store
  - .set(CONSENSUS_KEY, Value::Ed25519PrivateKey(consensus_key))?;
  - Ok(())
  + .export_private_key(CONSENSUS_KEY)
  + .map_err(|e| e.into())
  }
  pub fn epoch(&self) -> Result<u64> {
  