Allow loading the webviewer with empty src

Built the source based on: legalthings/pdf.js#5
Small change, but allows us to initialize the webviewer properly, without an actual pdf in it. Otherwise the empty viewer looks broken.

Updated build files based on v1.6.210 release of mozilla/pdf.js source

Merge pull request #10 from tmcdos/master

Upgrade viewer to PDF.js v1.6.210

Make css valid

Merge pull request #7 from legalthings/fix-css

Make css valid by removing unnecessary .pdf

Upgrade instructions

Merge pull request #6 from legalthings/upgrade-instructions

Upgrade instructions

Fixup guessing worker url if none was set

See #4 for more information.

Load worker script through XHR

See #4 for more information.

Added missing print containers

This should allow users to print pdf's again.

Minus js errors and warnings

Solved a number of errors and warnings caused by the non-standard using of pdf.js.

Added interpolation syntax for less variables in a string

Before:
url(@pdfjsImagePath/shadow.png)

After:
url('@{pdfjsImagePath}/shadow.png')

Fixup viewer.less

v0.2.1

Applied patches manually to viewer.less