Add defaults(), find_key(), find_last_key(), for_in(), functions(), ...

...has() and is_<type>()'s

```dict()``` objects in Python aren't ordered and don't inherit properties like Javascript. So:

```for_in = for_in_right = for_own = for_own_right```
This will conflict with the module `functions`. So you wouldn't be able to do `import pydash; pydash.functions.<func>` or `from pydash import functions; functions.<func>`.