fix view so new content is editable

and removed explicit use of internal model.attributes
add modal that shows unsaved changes
remotely adding new content now updates the ToC
remotely updated content now reloads Aloha
fix a timing issue when loading remotely-added content

when the nav document updates before the OPF updates the XhtmlFile for
the new content linked to in the nav file does not yet exist in
allContent
Merge pull request #14 from oerpub/phil-assorted

Add "Unsaved Changes" and fixup some collaboration cases