The goals:
* Maintain current security regarding content restrictions and content filtering in existing apps/modules.
* Maintain/allow privacy settings and restrictions on stored items of existing modules/apps.
* Allow addon devs to store and retrieve arbitrary unfiltered data for use by their addon.
* Allow arbitrary unfiltered data to be assigned privacy settings and restrictions consistent with other modules/apps.
* Provide a mechanism for unfiltered addon data to be cloned to channel clones. (Nomadic identity remains in tact even if the addon is not installed and running on the clone's hub - the data will not be used without the addon (unless it's accessible through the cloud/file interface), but it will exist in the even that the addon is installed and activated in the future).

Proposed solution:
* A standardized interface for addons to track/access and save and retrieve data in the existing attachment file store as an arbitrary data store.

Implementation suggestion:
* add an "attconfig" table (k/v store) and utilities for items in the attach table that mirrors pconfig, iconfig, abconfig, etc. for storage and search of addon-specific attributes.
* add an "addon" column to the attach table to track the originating addon
* implement an interface for the content column (insert/update) (attach.os_storage = 0) to store arbitrary data in the database
* implement an interface for os file contents (attach.os_storage = 1) for addons that may want to allow WebDAV file based updates to addon data.