Folders - Message posting, listing & deleting
JSDoc / code cleanup in folder/discussion comments
Added a folder-comment activity
Reprocessing folders when one of their content item’s their visibility changes
Rename folder-message to folder-comment
Regenerate preview images when a folder’s visibility changes
Merge branch 'folders-messages' of https://github.com/simong/Hilary into folders-messages
Added some documentation fixes to folder commenting
Add folders to the `message` activity stream
Merge branch 'folders-messages' of https://github.com/simong/Hilary into folders-messages
Renamed CREATED_MESSAGE to CREATED_COMMENT in folders/search
Merge remote-tracking branch 'nico/folders-messages' into folders-messages

* nico/folders-messages: (29 commits)
  Added some documentation fixes to folder commenting
  Tweaked test failure documentation
  Double escaping linebreaks in travis
  Prepending Travis’s cassandra-env with sed
  Moved redbac require to the top of the locking file
  Added missing locking documentation
  use redback for locking
  log error on failing to get a lock
  remove call to nonexistant callback
  Added link to ElasticSearch Terms Lookup filter documentation page
  Only parsing previews if there is a key present
  Use the search `resource_memberships` to filter resources by direct access
  tell the travis bot not to join/part the irc channel
  Added `isPrivate` to the /me feed’s tenant object
  Formatted Shibboleth README so it displays better on GitHub
  Added Welsh as language
  Giving Cassandra some time to start-up
  Add content item to folder via REST api for failing folders tests
  Removed tailing of cassandra logs on travis
  Delete child documents via a term query rather than has_parent
  ...
Merge branch 'folders-messages' of https://github.com/simong/Hilary into folders-messages
Remove/Inserting content from/in a folder on content visibility updates

I also refactored the light-weight folders stuff as it was only confusing
Merge branch 'folders-messages' of https://github.com/simong/Hilary into folders-messages
Fixed up some JSDoc
Fixed up some folder comments documentation
Merge branch 'folders-messages' of https://github.com/simong/Hilary into folders-messages

Conflicts:
	node_modules/oae-authz/lib/util.js
	node_modules/oae-folders/lib/library.js