Directories resource

Add the Client to the package
Also add the directories resource

I made two interfaces to the lookup function:
```python
c.directories.lookup.profile(term='...')
c.directories.lookup(term='...', profile='profile')
```

I think the later will be more useful than a direct mapping to the REST API because the profile won't be
known before runtime.

```python
def lookup_no_profile_param(term, profile):
    c.directories.lookup.getattr(profile)(term=term)

def lookup_with_profile_param(term, profile):
    c.directories.lookup(term=term, profile=profile)
```