Update spreadsheet.js to handle quotes cells

As reported in https://groups.google.com/d/msgid/dataverse-community/ef52665f-2348-413b-9181-0aad860316c1n%40googlegroups.com?utm_medium=email&utm_source=footer, the current previewer isn't handling cells that are in quotes (and have a comma inside them). 

This PR tries to address that by setting the quoteChar used during parsing. Alternately, we may need to set delimitersToGuess: to avoid all but the correct one for a given mimetype.

previewers/betatest/js/spreadsheet.js

@@ -23,7 +23,8 @@ function writeContent(fileUrl, file, title, authors) {
           var csv = e.target.result;
           var data = Papa.parse(csv, {
             header: true,
-            skipEmptyLines: true
+            skipEmptyLines: true,
+            quoteChar:'"'
           })
 
           handsontableContainer.innerHTML = '';
@@ -42,4 +43,4 @@ function writeContent(fileUrl, file, title, authors) {
     request.send();
 }
 
-
+