Patch biblio, CiteProc was looking for empty variables but wasn't trimming the variable before it was checked to be empty, so if there was a space entered into the field, it's no longer empty.  #2160
Merge pull request #2211 from openscholar/2160-trim-biblio-whitespace

Patch CSL to not only check for empty, but trimmed fields as well to prevent errant punctuation from showing in citation.