chore: move core modules into core directory

BREAKING CHANGE:
    This change moves the http module into angular2/, so its import
    path is now angular2/http instead of http/http.

    Many other modules have also been moved around inside of angular2,
    but the public API paths have not changed as of this commit.

modules/angular2/src/core/services/ruler.ts

@@ -0,0 +1,34 @@
+import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
+import {DomAdapter} from 'angular2/src/dom/dom_adapter';
+import {ElementRef} from 'angular2/src/core/compiler/element_ref';
+
+export class Rectangle {
+  left;
+  right;
+  top;
+  bottom;
+  height;
+  width;
+  constructor(left, top, width, height) {
+    this.left = left;
+    this.right = left + width;
+    this.top = top;
+    this.bottom = top + height;
+    this.height = height;
+    this.width = width;
+  }
+}
+
+export class Ruler {
+  domAdapter: DomAdapter;
+  constructor(domAdapter: DomAdapter) { this.domAdapter = domAdapter; }
+
+  measure(el: ElementRef): Promise<Rectangle> {
+    var clntRect = <any>this.domAdapter.getBoundingClientRect(el.nativeElement);
+
+    // even if getBoundingClientRect is synchronous we use async API in preparation for further
+    // changes
+    return PromiseWrapper.resolve(
+        new Rectangle(clntRect.left, clntRect.top, clntRect.width, clntRect.height));
+  }
+}