Renaming

Capturing this conversations from a few different places to the soon to be public repo. The top level package is currently `cudapython`, however we would like to rename it to `cuda` since having python in the package name is redundant. 

```
from cudapython import cuda, nvrtc
```
becomes...
```
from cuda import cuda, nvrtc
```

The PIP and conda package will be `cuda`.

cc @jakirkham 