fix(di): removed default visibility

BREAKING CHANGE:
    Directives will use the Unbounded visibility by default, whereas before the change they used Self

modules/angular2/src/core/annotations_impl/annotations.ts

@@ -1,6 +1,6 @@
 import {CONST, CONST_EXPR} from 'angular2/src/facade/lang';
 import {List} from 'angular2/src/facade/collection';
-import {InjectableMetadata, self} from 'angular2/src/di/metadata';
+import {InjectableMetadata} from 'angular2/src/di/metadata';
 import {DEFAULT} from 'angular2/change_detection';
 
 /**
@@ -792,7 +792,7 @@ export class Directive extends InjectableMetadata {
     exportAs?: string,
     compileChildren?: boolean,
   } = {}) {
-    super(self);
+    super();
     this.selector = selector;
     this.properties = properties;
     this.events = events;

modules/angular2/src/core/compiler/element_injector.ts

@@ -26,8 +26,7 @@ import {
   CyclicDependencyError,
   resolveForwardRef,
   VisibilityMetadata,
-  DependencyProvider,
-  self
+  DependencyProvider
 } from 'angular2/di';
 import {
   InjectorInlineStrategy,