move stuff to plpgsql

sql/website_exists.sql

@@ -0,0 +1,12 @@
+CREATE OR REPLACE FUNCTION website_exists(in_website_name text) RETURNS boolean AS $$
+BEGIN
+	PERFORM * FROM website w
+	WHERE w.name = in_website_name;
+
+    IF FOUND THEN
+        RETURN 1;
+	ELSE
+		RETURN 0;
+    END IF;
+END;
+$$ LANGUAGE plpgsql STRICT;