refactor(build): replace Gulp build with Webpack

Address part of angular-ui#1096 and angular-ui#1966.

Author: jrbotros

.eslintrc.js

@@ -0,0 +1,12 @@
+module.exports = {
+  extends: 'airbnb',
+  installedESLint: true,
+  rules: {
+    'no-control-regex': 'off',
+    'no-param-reassign': 'off',
+    'no-underscore-dangle': 'off',
+  },
+  settings: {
+    'import/resolver': 'webpack',
+  },
+};