add open_rsvps flag to music_sessions table

db/manifest

@@ -161,3 +161,4 @@ scheduled_sessions_2.sql
 scheduled_sessions_3.sql
 scheduled_sessions_cancel_all.sql
 scheduled_sessions_started_at.sql
+scheduled_sessions_open_rsvps.sql

db/up/scheduled_sessions_open_rsvps.sql

@@ -0,0 +1 @@
+alter table music_sessions add column open_rsvps boolean not null default false;