Food for thought...if we wanted, this line could be 
`base_layout_directory = getattr(settings, "ARMSTRONG_LAYOUT_BASE_DIRECTORY", "layout")`

I'd rather not introduce another setting though. If someone wants to change the directory, they can subclass our backend, change the attribute and point `ARMSTRONG_LAYOUT_BACKEND` to their new backend. So:
```
from armstrong.core.arm_layout.backends import BasicLayoutBackend
class MyBackend(BasicLayoutBackend):
    base_layout_directory = "my_layouts"

# in settings.py
ARMSTRONG_LAYOUT_BACKEND = "path.to.backend.MyBackend"
```