Add fallback certificate backend

src/cert/fallback.js

@@ -0,0 +1,21 @@
+'use strict';
+
+exports = module.exports = {
+    getCertificate: getCertificate,
+
+    // testing
+    _name: 'fallback'
+};
+
+var assert = require('assert'),
+    debug = require('debug')('box:cert/fallback.js');
+
+function getCertificate(domain, options, callback) {
+    assert.strictEqual(typeof domain, 'string');
+    assert.strictEqual(typeof options, 'object');
+    assert.strictEqual(typeof callback, 'function');
+
+    debug('getCertificate: using fallback certificate', domain);
+
+    return callback(null, 'cert/host.cert', 'cert/host.key');
+}