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

less/common/Badge.less

@@ -0,0 +1,38 @@
+.Badge {
+  .Badge--size(22px);
+  background: @muted-color;
+  color: #fff;
+  display: inline-block;
+  vertical-align: middle;
+  text-align: center;
+  .box-shadow(0 2px 4px @shadow-color);
+
+  .Badge-label {
+    display: none;
+  }
+}
+
+.Badge--size(@size) {
+  width: @size;
+  height: @size;
+  border-radius: @size / 2;
+  line-height: @size - 1px;
+
+  &, .Badge-icon {
+    font-size: 0.56 * @size;
+  }
+}
+
+.badges {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+
+  &, > li {
+    display: inline-block;
+  }
+}
+
+.Badge--hidden {
+  background: #888;
+}