refactor: rename annotations to metadata

BREAKING CHANGE (maybe)

Well as long as our customers use public API this should not be a
breaking change, but we have changed import structure as well as
internal names, so it could be breaking.

import:
  angular2/annotations => angular2/metadata

Classes:
  *Annotations => *Metadata
  renderer.DirectiveMetadata => renderer.RendererDirectiveMetadata
  renderer.ElementBinder => renderer.RendererElementBinder
  impl.Directive => impl.DirectiveMetadata
  impl.Component => impl.ComponentMetadata
  impl.View => impl.ViewMetadata

Closes #3660

modules/angular2/metadata.ts

@@ -0,0 +1,48 @@
+/**
+ * @module
+ * @description
+ *
+ * Annotations provide the additional information that Angular requires in order to run your
+ * application. This module
+ * contains {@link ComponentMetadata}, {@link DirectiveMetadata}, and {@link ViewMetadata}
+ * annotations, as well as
+ * the {@link Host} annotation that is used by Angular to resolve dependencies.
+ *
+ */
+
+export {
+  ComponentMetadata,
+  DirectiveMetadata,
+  PipeMetadata,
+  LifecycleEvent,
+  ViewMetadata,
+  ViewEncapsulation,
+  QueryMetadata,
+  AttributeMetadata,
+  Attribute,
+  AttributeFactory,
+  Component,
+  ComponentDecorator,
+  ComponentFactory,
+  Directive,
+  DirectiveDecorator,
+  DirectiveFactory,
+  View,
+  ViewDecorator,
+  ViewFactory,
+  Query,
+  QueryFactory,
+  ViewQuery,
+  Pipe,
+  PipeFactory
+} from './src/core/metadata';
+
+export {
+  OnAllChangesDone,
+  OnChange,
+  OnDestroy,
+  OnInit,
+  OnCheck
+} from './src/core/compiler/interfaces';
+
+export {Class, ClassDefinition, TypeDecorator} from './src/util/decorators';