Upgrade to TypeScript 2.1, and latest grunt-ts. (#3609)

* Upgrade to TypeScript 2.1, and latest grunt-ts.
* Remove AudioBuffer and UIEvent from the definitions, we now should be compatible with dom
* Update the tns-platform-declarations readme

tns-core-modules/declarations.d.ts

@@ -42,6 +42,24 @@ declare class Headers {
     set(name: string, value: string): void;
 }
 
+interface Blob {
+    readonly size: number;
+    readonly type: string;
+    msClose(): void;
+    msDetachStream(): any;
+    slice(start?: number, end?: number, contentType?: string): Blob;
+}
+
+declare var Blob: {
+    prototype: Blob;
+    new (blobParts?: any[], options?: BlobPropertyBag): Blob;
+}
+
+interface BlobPropertyBag {
+    type?: string;
+    endings?: string;
+}
+
 declare class Body {
     bodyUsed: boolean;
     /*
@@ -80,10 +98,6 @@ declare type RequestInfo = Request|string;
 
 declare function fetch(url: string, init?: RequestInit): Promise<Response>;
 
-interface XMLHttpRequest {
-    send(data?: FormData): void;
-}
-
 interface Console {
     time(reportName: string): void;
     timeEnd(reportName: string): void;
@@ -166,3 +180,7 @@ declare var exports: any;
 interface Array<T> {
     filter<U extends T>(pred: (a: T) => a is U): U[];
 }
+
+//Dialogs
+declare function alert(message?: any): void;
+declare function confirm(message?: string): boolean;