Support name and email from different directories

e.g.
1. Set karn.yml

```
/repos/repo:
  name: Adnan A
/repos:
  email: repo@repo.com
```
1. Run `$ karn update` in `/repos/repo`

Expected: both email and name updated to new identity: Adnan A repo@repo.com
Actual: only name is updated, email is unchanged
