Enable streaming in resource proxy

[domoritz]

Improves performance.

[vitorbaptista]

@domoritz How faster does it get, in your tests? Do you see any reason for not doing it? Also, I get adding stream=True to the requests, but why did you remove decode_unicode=False?

[domoritz]

@vitorbaptista The performance difference is sadly to very noticeable because it is not possible to send part of the response before we have downloaded the whole file. However, I should have added streaming=True in the first place because if there is a large file without a content-length header, we would download the whole file. And this wouldn't work. I removed decode_unicode=False because it is the default.

[amercader]

@vitorbaptista I took this off your hands and merged it, as it was needed for other PRs, thanks!

[vitorbaptista]

@amercader Great! Sorry for keeping it for too long 👍