Rename Sponsor model to Sponsorship

[alvarocasadoc]

Rename this model to the correct name and check all dependencies in our code.

[noloman]

do we also want to rename the table, or just the model?

[alvarocasadoc]

I would rename both the model and the table to keep the same naming across the whole project.

[noloman]

I would rename both the model and the table to keep the same naming across the whole project.

awesome! just as I imagined. I will assign the issue to myself if it's OK!