Quilt module: Add configurable size limit on files fetched from caches

[nevali]

There is a point at which librdf will take too long to parse some RDF for our purposes when it becomes sufficiently large. We can avoid this occurring by failing requests within our cURL write-handler if they exceed a certain size limit.

This would work around (but not fix) #87, ensuring some level of service for the affected entities.

Internal tracking: RESDATA-1127