pdfs on PMC result list

pdf attachments were not showing up in the result lists of PMC, added them, and also did some cleanup and refactoring.

is there a way to have a real test for a result list? the test added just shows that the page would return multiple...
Actually, I think we should. IMO that is always less confusing. Imagine that you have two results on page and one of them fails to retrieve the `pmcid`, so then you automatically import one of the two results. I know we do this in a couple translators, but I generally think this is a bad idea. @adam3smith, thoughts?