Adding a bunch of gulp utilities

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

gulp-sass/gulp-sass-tests.ts

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+/// <reference path="./gulp-sass.d.ts"/>
+/// <reference path="../gulp/gulp.d.ts"/>
+import gulp = require("gulp");
+import sass = require("gulp-sass");
+
+gulp.task('sass', function () {
+    gulp.src('./scss/*.scss')
+        .pipe(sass())
+        .pipe(gulp.dest('./css'));
+});
+
+gulp.task('sass', function () {
+    gulp.src('./scss/*.scss')
+        .pipe(sass({errLogToConsole: true}))
+        .pipe(gulp.dest('./css'));
+});

gulp-sass/gulp-sass.d.ts

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+// Type definitions for gulp-sass
+// Project: https://github.com/dlmanning/gulp-sass
+// Definitions by: Asana <https://asana.com>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../node/node.d.ts"/>
+
+declare module "gulp-sass" {
+    interface SassResults {
+        css: string;
+        map: string;
+        stats: {
+            entry: string;
+            start: Date;
+            end: Date;
+            duration: number;
+            includedFiles: string[];
+        }
+    }
+
+    interface SassOptions {
+        file?: string;
+        data?: string;
+        success?: (results: SassResults) => any;
+        error?: (err: Error) => any;
+        includePaths?: string[];
+        imagePaths?: string[];
+        indentedSyntax?: boolean;
+        omitSourceMapUrl?: boolean;
+        outFile?: string;
+        outputStyle?: string;
+        precision?: number;
+        sourceComments?: boolean;
+        sourceMap?: boolean | string;
+        sourceMapEmbed?: boolean;
+        sourceMapContents?: boolean;
+    }
+
+    interface Options extends SassOptions {
+        errLogToConsole?: boolean;
+        onSuccess?: (css: string) => any;
+        onError?: (err: Error) => any;
+        sync?: boolean;
+    }
+
+    function sass(opts?: Options): NodeJS.ReadWriteStream;
+
+    export = sass;
+}