Webpack (#1367)

* Replace gulp with webpack and npm scripts for JS compilation
* Set up Travis CI to commit compiled JS
* Restructure `js` directory; only one instance of npm, forum/admin are "submodules"
* Refactor JS initializers into Application subclasses
* Maintain partial compatibility API (importing from absolute paths) for extensions
* Remove minification responsibility from PHP asset compiler
* Restructure `less` directory

js/src/common/Session.js

@@ -0,0 +1,49 @@
+/**
+ * The `Session` class defines the current user session. It stores a reference
+ * to the current authenticated user, and provides methods to log in/out.
+ */
+export default class Session {
+  constructor(user, csrfToken) {
+    /**
+     * The current authenticated user.
+     *
+     * @type {User|null}
+     * @public
+     */
+    this.user = user;
+
+    /**
+     * The CSRF token.
+     *
+     * @type {String|null}
+     * @public
+     */
+    this.csrfToken = csrfToken;
+  }
+
+  /**
+   * Attempt to log in a user.
+   *
+   * @param {String} identification The username/email.
+   * @param {String} password
+   * @param {Object} [options]
+   * @return {Promise}
+   * @public
+   */
+  login(data, options = {}) {
+    return app.request(Object.assign({
+      method: 'POST',
+      url: app.forum.attribute('baseUrl') + '/login',
+      data
+    }, options));
+  }
+
+  /**
+   * Log the user out.
+   *
+   * @public
+   */
+  logout() {
+    window.location = app.forum.attribute('baseUrl') + '/logout?token=' + this.csrfToken;
+  }
+}