Email HTML improvements

* Reduce max-width of indented activity comment containers
* Expand width for the activity summary
Using new activity-comment form for rendering nested comments in the email template
Update README.md to reflect extra steps for Etherpad configuration after skinning work
Follow up after review
remove publish endpoint
mover permisssion model to principals
move permissions model to principals module
use common permissions model
move messages models to message-box module
add documentation for REST models
Use oae-rest from npm
Consolidate joinPad and getPadUrl parameters
Merge branch 'master' of https://github.com/sakaiproject/Hilary into issue-3844
order required properties first
Merge branch 'master' of https://github.com/oaeproject/Hilary into restdoc
Merge branch 'master' of https://github.com/oaeproject/Hilary into restdoc-content

Conflicts:
	node_modules/oae-content/lib/rest.js
Switch order in oae-tenants rest.js
Renamed collections to folders
Fixed ordering of oae packages in package.json
Merge branch 'restdoc-search' of https://github.com/sathomas/Hilary into restdoc-search