Only send back size and content_type if they exist
Only send back size and content_type if they exist

cosenal/waterbutler,chrisseto/waterbutler,Ghalko/waterbutler,hmoco/waterbutler,icereval/waterbutler,Johnetordoff/waterbutler,rdhyee/waterbutler,kwierman/waterbutler,rafaeldelucena/waterbutler,TomBaxter/waterbutler,RCOSDP/waterbutler,CenterForOpenScience/waterbutler,felliott/waterbutler