Adding a bunch of gulp utilities

This should allow a developer to write a gulpfile in TypeScript to
compile a TypeScript project.

gulp-sourcemaps/gulp-sourcemaps.d.ts

@@ -0,0 +1,28 @@
+// Type definitions for gulp-sourcemaps
+// Project: https://github.com/floridoo/gulp-sourcemaps
+// Definitions by: Asana <https://asana.com>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../node/node.d.ts"/>
+
+declare module "gulp-sourcemaps" {
+    interface InitOptions {
+        loadMaps?: boolean;
+        debug?: boolean;
+    }
+
+    interface WriteMapper {
+        (file: string): string;
+    }
+
+    interface WriteOptions {
+        addComment?: boolean;
+        includeContext?: boolean;
+        sourceRoot?: string | WriteMapper;
+        sourceMappingURLPrefix?: string | WriteMapper;
+    }
+
+    export function init(opts?: InitOptions): NodeJS.ReadWriteStream;
+    export function write(opts?: WriteOptions): NodeJS.ReadWriteStream;
+    export function write(path?: string, opts?: WriteOptions): NodeJS.ReadWriteStream;
+}