Verbose mode

It might be useful if the scripts could be ran in verbose mode. In which mode each command would be printed before execute.

```Makefile
echo:
echo foo
```

Run `bake --verbose echo` with above Bakefile:

```
+ Executing echo:
| + echo foo
| foo
+ Done.
```

#### Alternatives:

I found the `--debug` option, but it is too verbose to be used in actual usage: it prints bake internal stuff. Also, the option is hidden.

Begin at the CLI handling for `bake --verbose echo` and compare it with the existing `--debug` option. Done means commands are printed before execution in the demonstrated format, without exposing the internal debug output described in the issue.

Written by the indexing model from the issue text.