More work on counts for paper routes as part of #125

[josmas]

• a bit of refactoring on papers/badges[/count]
• new endpoints for three last routes in papers, with tests.

This is part of the work in #125 for the /papers route.

[josmas]

I have also added counts for the /badges route.

[josmas]

Last piece of work for #125 is in now (user count route). I have also refactored a bit so that the code is consistent with other routes in both /users and /papers.

@acabunoc this is a large change, take your time reviewing; there are tests for all the routes, which should make things easier.

[abbycabs]

Thanks @josmas! I'll try to review today :)

[abbycabs]

This looks good to me! R+ once you update the assert for /papers/:doi1/:doi2/users/:orcid/badges/:badge/count

Feel free to merge once that's in :) Thanks for this, it's a huge lift!