We are going to move to this code organization for
managing streams:
stream_create.js
stream_create_subscribers.js
stream_edit.js
stream_edit_subscribers.js
The modules stream_create.js and stream_edit.js historically
manage the entire process of creating and editing stream
data (respectively).
Going forward both will delegate most of the subscriber-specific
pieces to either stream_create_subscribers or stream_edit_subscribers.
The stream_*_subscribers modules will be somewhat similar in
nature, but the way that we manage subscribers at creation time
is a bit different than how we manage subscribers at edit time.