ldap: unique index names for the database, fixes non-creating of indexes for the second table and potential issues in the app

Create a new OC_Share object instead of manually inserting rows when adding a user to a group share, prevents a couple of potential bugs

from http://mozilla.github.com/pdf.js/build/pdf.js

README added to document the fact stated above
update.sh added for easy update of pdfjs

CAUTION:
Don't update before OC4! API has been changed and we need to adopt files_pdfviewer

                header('X-Frame-Options: Sameorigin');
                header('X-XSS-Protection: 1; mode=block');
                header('X-Content-Type-Options: nosniff');

Thanks to Lukas Reschke for reporting this issue (and many more).

Name conflict with two FileUploads :-P