##### SUMMARY
Customer request: When typing the string to encrypt, it shows up as plain text. Since the string is being encrypted, it's safe to assume that it's sensitive (e.g. passwords) and should therefore be hidden. At the very least, maybe this could be a command line option. If it is hidden, I'd prefer to be forced to enter it twice to avoid mismatch. To mitigate this issue, I am currently using "stty -echo", but that shouldn't be necessary.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
ansible-vault
options = super(VaultCLI, self).post_process_args(options)
        display.verbosity = options.verbosity
        if options.vault_ids:
            for vault_id in options.vault_ids:
                if u';' in vault_id:
                    raise AnsibleOptionsError("'%s' is not a valid vault id. The character ';' is not allowed in vault ids" % vault_id)
        if getattr(options, 'output_file', None) and len(options.args) > 1:
            raise AnsibleOptionsError("At most one input file may be used with the --output option")
        if options.action == 'encrypt_string':
            if '-' in options.args or not options.args or options.encrypt_string_stdin_name:
                self.encrypt_string_read_stdin = True
            
            if options.encrypt_string_prompt and self.encrypt_string_read_stdin:
                raise AnsibleOptionsError('The --prompt option is not supported if also reading input from stdin')
        return options
    def run(self):