Rename package

[moggers87]

There's another python package using the sendfile package name. We should also take this opportunity to move code out of __init__.py.

1. Rename package to something like django_sendfile
2. Move code from __init__.py to sendfile.py
3. Imports will now look like from django_sendfile import sendfile

[alexandresebrao]

I want to know if we could suggest a new name to the package than sendfile. I don't like sendfile at all. django-xsendfile would make more sense to me.

[moggers87]

@alexandresebrao no, I'm not interested in doing that. This issue is only for renaming the folder where the package is installed to avoid potential conflicts

[bors-ltd]

I must add I found this package because I was desperately looking for a maintained version of django-sendfile. I may have missed it with another name...

Thanks for your work at maintaining this useful little piece of code!