feat(package): introduce a catch-all package angular.

modules/angular has no implementation, but depends on all the pieces
that make angular - core, di, directives, etc. It is the package that
all client apps will depend on.

modules/angular/pubspec.yaml

@@ -0,0 +1,20 @@
+name: angular
+version: 2.0.0-alpha.1
+environment:
+  sdk: '>=1.4.0'
+dependencies:
+  stack_trace: '1.1.1'
+  change_detection:
+    path: ../change_detection
+  di:
+    path: ../di
+  facade:
+    path: ../facade
+  reflection:
+    path: ../reflection
+  directives:
+    path: ../directives
+dev_dependencies:
+  test_lib:
+    path: ../test_lib
+  guinness: ">=0.1.16 <0.2.0"

modules/angular/src/angular.js

@@ -0,0 +1,6 @@
+/**
+ * Define public API for Angular here.
+ */
+export * from 'change_detection/change_detection';
+export * from 'core/core';
+export * from 'directives/directives';