Puts body of PDFjs viewer.html into pdf handlebars template.
Loads pdfjs files and sets defaults in topics.html.
Adds interim changes to make pdfjs initialize from within Backbone.
Adds basic styles for pdf container.
Modifies viewer.css and viewer.js to prevent unwanted automagic.
Reenables points tracking for pdf views.
Prevents pdfjs setting document title to pdf URL.
More robustly check if DOMElement is undefined when unbinding listenToDOM.
Prevent pdfjs toolbar from popping over modals and sidebar.
Merge pull request #2609 from rtibbles/pdfjs_robust

Run PDFJS directly, not within an iFrame