allow to specify User-agent (or headers in general)

[vladak]

Today I got an e-mail from Flickr, informing that API calls will have to supply the 'User-Agent' header and there is some discussion raging on https://www.flickr.com/groups/api/discuss/72157721918374433/72157721918403334/. Given that flickrapi uses the requests module, which sends a non-empty User-Agent header by default (even if one supplies the 'headers' parameter), I think we are good here for now.

That said, it would be nice to be able to specify a custom (User-Agent) header (or just a bunch of custom headers in the form of dictionary) when creating the FlickrAPI object.

Or maybe override the default 'User-agent' header with something like flickrapi/3.0.dev0 or such by default.

[drsybren]

It would seem that the decision has been reverted already: https://www.flickr.com/groups/51035612836@N01/discuss/72157721918374433/72157721918411949

Regardless, this could be a nice feature.