send a strong etag for the output.pdf file, needed for byte ranges in pdf.js
send a strong etag for the output.pdf file, needed for byte ranges in pdf.js

fancycharts/clsi-sharelatex,dwrensha/clsi-sharelatex,fancycharts/clsi-sharelatex,dwrensha/clsi-sharelatex,sharelatex/clsi-sharelatex,sharelatex/clsi-sharelatex,EDP-Sciences/clsi-sharelatex