[CHEF-4421] Improve an error message "No cookbook found".

JIRA: http://tickets.opscode.com/browse/CHEF-4421

When no cookbook is found in `cookbook_path` directory, `chef-client` or `chef-solo` prints an error message.

When `cookbook_path` is `["/path/dir/a", "/path/dir/b"]`, `/path/dir/a` has a cookbook, `/path/dir/b` has no cookbook and I run `chef-client`, I get the following message:

```
No cookbook found in ["/path/dir/a", "/path/dir/b"], make sure cookbook_path is set correctly.
```

This is confusing and **user may think both `/path/dir/a` and `/path/dir/b` have no cookbook**.

With this pull request, you will get a straightforward message like the following:

```
No cookbook found in /path/dir/b, make sure cookbook_path is set correctly.
```