Register Iterable instead of Sequence for dumps?

[wsanchez]

I was looking at the code and noticed that in converters.py:38, you use a Sequence where an Iterable would work for more object types.

Looking at _dump_seq, all it does it iterate over the given seq, so no other change should be needed.

[Tinche]

Why not? Try making the change and if the tests pass, submit a PR and I'll take a look :)