Fix printing behaviour in Chrome

Two major issues:
1. Border/shadow around every page. Removed by adding "border:none".
2. Added "overflow:visible" (overrides "overflow:auto") in #viewContainer.
   This solves two problems:
   - It prevents scrollbars from appearing.
   - Every "page" is automatically resized to fit on a printed page,
     just like the Firefox.
To see what's wrong, here's a picture of how PDF.js rendered the pdf in
 Chrome (using "Print to PDF" feature of Chrome):
 https://robwu.nl/pdfjs/pdfjs-print-with-chromium-28.pdf

Successfully tested with Chrome 28 and Firefox 22.

Solves #3445
Bug 881152 - hdpi/xhdpi resolution assets and layout for PDF Viewer app
 1. Add 1.5x assets
 2. specify the background size of page number section
Merge pull request #3479 from RudyLu/mutlires_1.5

Bug 881152 - hdpi/xhdpi resolution assets and layout for PDF Viewer app
Merge pull request #3473 from Rob--W/chrome-printing

Fix printing behaviour in Chrome