Draft of attribute syntax API

Excuse me, I did not understand well this subject.

I think you **must** escape the dot when using chef tools:

```
$ knife node show web001.example.com -a "myapp.conf.settings\.yml.dbname"
```

In my own imaginary world, using `"myapp.conf.settings.yml.dbname"` should **not** return the desired value.

Regarding the fallback behavior (to avoid escaping), I think it's unnecessary magic for some cases like console tools or libraries: we know our stuff. While I understand that it can be useful in some other environments, more oriented to non-tech guys. But maybe that is the work of those *environment tools*, outside the Chef API/core. Or maybe not.

Can not think of an example of conflict right now,  but I prefer to be cautious in these cases. Personally I am of those who is confused by this ambiguous behaviors when I'm learning something new.