#21: Oops! Forgot the organisers

Also tidied up the 'add-user-table' migration, which was actually just part of the how-to-get-started-with-migratus stuff and we don't need.

resources/migrations/20170315190500-roles-and-teams.up.sql

@@ -25,6 +25,10 @@ create table if not exists teammemberships (
   canvasser_id integer not null references canvassers(id)
 );
 
+create table if not exists teamorganiserships (
+  team_id integer not null references teams(id),
+  canvasser_id integer not null references canvassers(id)
+);
 
 alter table roles owner to youyesyet;