Filter by channel_ids

* Filter key changed to channel_ids from channels
Filter drops list by read/unread state
River Collaborators

* Add/Remove collaborators implemented
* Modify pending ui changes for editor/readonly selection
Merge branch 'integration-dev' into rivers-ui-dev
Bucket collaborators implemented
Visual feedback

* Show loading message when creating, updating or deleting
rivers/channels takes too long.
* Show a system message on failure/success.