[Database v0006] Drop unused server.path field

- Fix "Field 'path' doesn't have a default value" errors

src/sql/migrations/down/0005.sql

@@ -0,0 +1,3 @@
+BEGIN;
+ALTER TABLE `server` ADD `path` varchar(190) NOT NULL DEFAULT '' AFTER `base_url`;
+COMMIT;

src/sql/migrations/up/0006.sql

@@ -0,0 +1,3 @@
+BEGIN;
+ALTER TABLE `server` DROP COLUMN `path`;
+COMMIT;