wsgi app picky about accepted mime-types

[mrvanes]

As discussed on Slack, I file an issue as a reminder of this problem.

On a fresh pyFF deploy (master as of feb 2020) I encountered an unexpected Accept header problem. Chrome sends application/xml as the third option in Accept header, but the wsgi app only parses the first one as can be seen on this line:

pyFF/src/pyff/api.py

Line 151 in a17e543

accept = str(request.accept).split(',')[0]

wsgi is clearly not intended to be viewed by browser, but that's how developers work. The result is that pyFF chooses the "when accept application/json" pipe instead of the application/xml, even though Chrome says it accepts application/xml. This caused quite some confusion and cost significant time before I understood the solution was as simple as changing my pipe to "when accept text/html" for (browser) testing.

[leifj]

Can you re-verify on the master branch.