Fix test since new pdfjs version.
Fix test since new pdfjs version.

- The default verbosity level is now set to `warnings`.
- We no longer get any warnings trying to setup fakeworkers.

senny/pdfjs_viewer-rails,senny/pdfjs_viewer-rails,gordonbisnor/pdfjs_viewer-rails,gordonbisnor/pdfjs_viewer-rails,senny/pdfjs_viewer-rails,gordonbisnor/pdfjs_viewer-rails