Updated docsplit processor for documents to create derivatives on the filesystem.
Adds internet archive book viewer.

NOTE: Had to upgrade bookviewer.js to use newer versions of jQuery/jQuery-UI and a few plugins. Future work will probably have to be done.
Fix broken bookreader CSS.
Fixed responsiveness of the document viewer.
Add public/media as a shared child, whilst it's a symlink.
Fixed .gitignore's public/media assertion.

[skip ci]
Merge pull request #163 from OregonDigital/feature/DocumentReader

Feature/document reader