Float-friendly replacement for Django's built-in add filter.

[centricle]

Float-friendly replacement for Django's built-in add filter.

[coveralls]

Coverage decreased (-1.49%) to 62.37% when pulling 537d5d6 on centricle:master into 4901e8d on dbrgn:master.

[dbrgn]

Thanks! Calling it sum solves the add conflict :)

[dbrgn]

Maybe call the function addition to avoid overloading Python's sum builtin?

[dbrgn]

Also, maybe add 2-3 tests involving Decimal (see other tests) to avoid decreasing the test coverage?

[coveralls]

Coverage decreased (-1.49%) to 62.37% when pulling 07e4562 on centricle:master into 4901e8d on dbrgn:master.

[centricle]

Huh. Coveralls is complaining about existing tests that weren't touched. I wonder if something changed on their end.

[dbrgn]

Huh, strange. Anyways, your PR looks good. Thanks!