Implementing batch deletes for calls, logs and routes

Partially-Closes: #302

api/models/logs.go

@@ -20,4 +20,6 @@ type LogStore interface {
 	// DeleteLog will remove the log at callID, it will not return an error if
 	// the log does not exist before removal.
 	DeleteLog(ctx context.Context, appName, callID string) error
+
+	BatchDeleteLogs(ctx context.Context, appName string) error
 }