style changes for layout of covers and doc
send pushstate to frontend
send mimetype for attachment model
send pdf.js viewer URL config
send all items instead of a single page
routing, events, and attachment model

- collection/attachmentbag, model/attachment, view/attachmentview
- appdispatch for global event aggregator
- router singleton
- event to show available attachments
- event to open attachment
pdf.js template setup
add bootstrap
add font-awesome
add pdf.js build