completion command is broken

```
> scrt completion bash
Error: missing storage type
Usage:
  scrt completion bash

Flags:
  -h, --help              help for bash
      --no-descriptions   disable completion descriptions

Global Flags:
  -c, --config string     configuration file
  -p, --password string   master password to unlock the store
      --storage string    storage type
  -v, --verbose           verbose output
```