Fix how we find if streams are muted.

This commit changes stream_data.in_home_view() to
take a stream_id parameter, which will make it more
robust to stream name changes.

This fixes a bug.  Now when an admin renames a stream
you are looking at, it will correctly show itself to
be un-muted. (Even with this fix, though, the stream
appears to be inactive.)

Some callers still do lookups by name, and they will
call name_in_home_view() for now, which we can
hopefully deprecate over time.

frontend_tests/node_tests/unread.js

@@ -151,6 +151,10 @@ var zero_counts = {
     assert.equal(count, 0);
 }());
 
+stream_data.get_stream_id = function () {
+    return 999;
+};
+
 (function test_muting() {
     stream_data.is_subscribed = function () {
         return true;