fix: set default theme

Author: Ido Shamun

migrations/20180907232401_default_theme.js

@@ -0,0 +1,6 @@
+exports.up = knex =>
+  knex.schema.table('settings', (table) => {
+    table.string('theme').defaultTo('darcula').alter();
+  });
+
+exports.down = () => Promise.resolve();