Issue 305 broken link because of language fixes (#322)

* without having having to worry about site design.

Let me know if double having is intentional

* distinguish case of no translation and en lang

* prettier recommends

* distinguish case of no translation and en lang

* prettier recommends

* merge with latest origin/master changes

* typo

* link with language fixes

* do not show language dropdown if only one enabled

* check translation outside of LanguageDropDown.render

lib/server/env.js

@@ -0,0 +1,66 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const CWD = process.cwd();
+const fs = require('fs-extra');
+const path = require('path');
+
+const join = path.join;
+
+const languages_js = join(CWD, 'languages.js');
+const versions_json = join(CWD, 'versions.json');
+
+class Translation {
+  constructor() {
+    this.enabled = false;
+    this.languages = [
+      {
+        enabled: true,
+        name: 'English',
+        tag: 'en',
+      },
+    ];
+
+    this._load();
+  }
+
+  enabledLanguages() {
+    return this.languages.filter(lang => lang.enabled);
+  }
+
+  _load() {
+    if (fs.existsSync(languages_js)) {
+      this.enabled = true;
+      this.languages = require(languages_js);
+    }
+  }
+}
+
+class Versioning {
+  constructor() {
+    this.enabled = false;
+    this.latestVersion = null;
+    this.versions = [];
+
+    this._load();
+  }
+
+  _load() {
+    if (fs.existsSync(versions_json)) {
+      this.enabled = true;
+      this.versions = JSON.parse(fs.readFileSync(versions_json, 'utf8'));
+      this.latestVersion = this.versions[0];
+    }
+  }
+}
+
+const env = {
+  translation: new Translation(),
+  versioning: new Versioning(),
+};
+
+module.exports = env;