Close all connections for a postgres db

Useful to drop a db quickly…

``` SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE pg_stat_activity.datname = 'myDB' AND pid <> pg_backend_pid();

```

From: https://stackoverflow.com/questions/5408156/how-to-drop-a-postgresql-database-if-there-are-active-connections-to-it