Adding a bunch of gulp utilities

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

gulp-autoprefixer/gulp-autoprefixer-tests.ts

@@ -0,0 +1,20 @@
+/// <reference path="./gulp-autoprefixer.d.ts"/>
+/// <reference path="../gulp/gulp.d.ts"/>
+import gulp = require("gulp");
+import autoprefixer = require("gulp-autoprefixer");
+
+gulp.src("test.css")
+    .pipe(autoprefixer())
+    .pipe(gulp.dest("build"));
+
+gulp.src("test.css")
+    .pipe(autoprefixer({ browsers: ["Chrome"]}))
+    .pipe(gulp.dest("build"));
+
+gulp.src("test.css")
+    .pipe(autoprefixer({cascade: false}))
+    .pipe(gulp.dest("build"));
+
+gulp.src("test.css")
+    .pipe(autoprefixer({remove: false}))
+    .pipe(gulp.dest("build"));

gulp-autoprefixer/gulp-autoprefixer.d.ts

@@ -0,0 +1,18 @@
+// Type definitions for gulp-autoprefixer
+// Project: https://github.com/sindresorhus/gulp-autoprefixer
+// Definitions by: Asana <https://asana.com>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../node/node.d.ts"/>
+
+declare module "gulp-autoprefixer" {
+    interface Options {
+        browsers?: string[];
+        cascade?: boolean;
+        remove?: boolean;
+    }
+
+    function autoPrefixer(opts?: Options): NodeJS.ReadWriteStream;
+
+    export = autoPrefixer;
+}