Add secrets table

this will hold keys, certs etc

migrations/schema.sql

@@ -264,4 +264,9 @@ CREATE TABLE IF NOT EXISTS appMounts(
     FOREIGN KEY(appId) REFERENCES apps(id),
     FOREIGN KEY(volumeId) REFERENCES volumes(id));
 
+CREATE TABLE IF NOT EXISTS secrets(
+    name VARCHAR(128) NOT NULL UNIQUE,
+    value TEXT,
+    PRIMARY KEY(name));
+
 CHARACTER SET utf8 COLLATE utf8_bin;