Salt remains the same across sessions

For Fernet to work correctly, the salt must be the same when
re-encrypting the project after a successful decryption.

This is because the key for decryption and encryption must be the
same during a single session. So if the project was decrypted with
one salt, the we want to generate a new salt to re-encrypt the file
with a new key, Fernet will cough up an exception. Presumably this
problem won't exist with other crypto-systems (e.g. AES-GCM).

pappyproxy/crypto.py

@@ -101,6 +101,7 @@ class Crypto(object):
                     # Quit pappy if user doesn't retry
                     # or if all retries exhuasted
                     if not self.confirm_password_retry() or retries <= 0:
+                        os.remove(self.config.archive)
                         return False
                     else:
                         self.password = None