Create an account for chain=dev (#5612)

* implement From<&'static str> for Secret

* Dev account.

* Fix Secret semantics.

ethstore/src/account/crypto.rs

@@ -122,7 +122,7 @@ impl Crypto {
 		}
 
 		let secret = self.do_decrypt(password, 32)?;
-		Ok(Secret::from_slice(&secret)?)
+		Ok(Secret::from_unsafe_slice(&secret)?)
 	}
 
 	/// Try to decrypt and return result as is

ethstore/src/presale.rs

@@ -50,7 +50,7 @@ impl PresaleWallet {
 		let len = crypto::aes::decrypt_cbc(&derived_key, &self.iv, &self.ciphertext, &mut key).map_err(|_| Error::InvalidPassword)?;
 		let unpadded = &key[..len];
 
-		let secret = Secret::from_slice(&unpadded.keccak256())?;
+		let secret = Secret::from_unsafe_slice(&unpadded.keccak256())?;
 		if let Ok(kp) = KeyPair::from_secret(secret) {
 			if kp.address() == self.address {
 				return Ok(kp)