This sets us up to use better system-wide data structures
for tracking subscribers.
Basically, instead of storing subscriber data on the
"sub" objects in stream_data.js, we instead have a
parallel data structure called stream_subscribers.
We also have stream_create, stream_edit, and friends
use helper functions rather than accessing
sub.subscribers directly.
Since the denmark stream stub has subscribed = true,
we include the current user id in it's subscribers set.
We remove user `me` from sweden stream stub for the same
reason.
This fixes the regression introduced in the pervious
commit to regain the 100% line coverage in `user_pill.js`
as well as `stream_pill.js`.
The new `stream_edit.js` mainly tests for:
* The stream related queries of the typeahead in `user_pill.js`
* The "Add subscribers" event handlers.
* The event handler which displays the settings for a stream.
Steve Howell
Anders Kaseorg
ryanreh99
Priyank Patel