add from_env to the config schema

src/server/models/config.js

@@ -18,7 +18,14 @@ module.exports = function(crowi) {
   configSchema = new mongoose.Schema({
     ns: { type: String, required: true, index: true },
     key: { type: String, required: true, index: true },
-    value: { type: String, required: true }
+    value: { type: String, required: true },
+    from_env: {type: Boolean, required: true}
+  });
+
+  configSchema.index({
+    ns: 1,
+    key: 1,
+    from_env: 1
   });
 
   function validateCrowi() {