Show correct log prefix for step summary message

Turns output from 

```
verb dullard Running steps:
verb dullard    wordpress-setup
verb dullard    setup
verb dullard    php-tags-transform
verb dullard    core
verb dullard    php-tags-revert
verb dullard    finish
verb dullard Running steps:
verb dullard    portal-dirs
verb dullard    wordpress-cwd
verb portal-dirs started
info portal-dirs complete in 3 milliseconds
```

into

```
verb default Running steps:
verb default    wordpress-setup
verb default    setup
verb default    php-tags-transform
verb default    core
verb default    php-tags-revert
verb default    finish
verb wordpress-setup Running steps:
verb wordpress-setup    portal-dirs
verb wordpress-setup    wordpress-cwd
verb portal-dirs started
info portal-dirs complete in 3 milliseconds
```

which is much more useful.