Add ability to manipualate option upload in settings.py

[Dean-Christian-Armada]

An example of this is when you want to avoid adding a suffix for every filename you to add unique_filename: False in the dictionary value of options variable in _upload. I did this manually changing the inside of the library.

[klis87]

Apologies I didnt reply, I didnt notice this issue. Anyway, I dont work with Django at the moment at all and I cannot spend time developing this library. I will gladly accept pull requests though.