Changed the default redis database to match rapid pro redis database

courier.toml

@@ -19,7 +19,7 @@ port = 8080
 db = "postgres://courier@localhost/courier?sslmode=disable"
 
 # Our redis connection string, path is our database. Rapid Pro uses 15 for the database (or 10 when testing) 
-redis = "redis://localhost:6379/0"
+redis = "redis://localhost:6379/15"
 
 # Our spool directory for storing messages when Redis is down, this must exist and be writeable
 spool_dir = "/var/spool/courier"