apply some defaults when loading the config

lib/load-config.js

@@ -18,5 +18,23 @@ try {
     }
     config = require("../config/config.example");
 }
+
+var isPositiveNumber = function (n) {
+    return (!isNaN(n) && n >= 0);
+};
+
+if (!isPositiveNumber(config.inactiveTime)) {
+    config.inactiveTime = 90;
+}
+if (!isPositiveNumber(config.archiveRetentionTime)) {
+    config.archiveRetentionTime = 90;
+}
+if (!isPositiveNumber(config.maxUploadSize)) {
+    config.maxUploadSize = 20 * 1024 * 1024;
+}
+if (!isPositiveNumber(config.defaultStorageLimit)) {
+    config.defaultStorageLimit = 50 * 1024 * 1024;
+}
+
 module.exports = config;