adding pdf to options


Hm...probably did this backwards by forking into the Aspace git account...oh well.

So, added the ability to pull PDFs. 

Really feel not good about this....EADs as well. If people are able to pull EAD xml and PDFs ( which require EAD XML) from large repositories, it would be really easy to bring the instance down to its knees  ( imagine  someone crawling a repo and download all the EADs and PDFs..) Wouldn't be a problem if people put Squid or Varnish in front...but we probably need to figure out a native way of caching these files, since they 1) probably don't change that often and 2) can really slam the DB.

But as a plugin now, I think it's good. 

but what do you think?