Ensure the GulpProxy class is assignable to Gulp, which was causing l…

…ots of downstream issues. (#1)

gulp-core-build/src/GulpProxy.ts

@@ -1,29 +1,26 @@
 import gulp = require('gulp');
+import Orchestrator = require('orchestrator');
 
 /* tslint:disable:max-line-length */
-export class GulpProxy {
+export class GulpProxy extends Orchestrator implements gulp.Gulp {
+  public src: gulp.SrcMethod;
+  public dest: gulp.DestMethod;
+  public watch: gulp.WatchMethod;
+
   private _gulp: gulp.Gulp;
 
   constructor(gulpInstance: gulp.Gulp) {
+    super();
     this._gulp = gulpInstance;
+    this.src = gulpInstance.src;
+    this.dest = gulpInstance.dest;
+    this.watch = gulpInstance.watch;
   }
 
-  public task(): void {
+  /* tslint:disable-next-line:no-any */
+  public task(): any {
     throw new Error(
       'You should not define gulp tasks, but instead subclass the GulpTask and override the executeTask method.'
     );
   }
-
-  public src(glob: string | string[], opt?: gulp.SrcOptions): NodeJS.ReadWriteStream {
-    return this._gulp.src(glob, opt);
-  }
-
-  public dest(outFolder: string | ((file: string) => string),
-    opt?: gulp.DestOptions): NodeJS.ReadWriteStream {
-    return this._gulp.dest(outFolder, opt);
-  }
-
-  public watch(glob: string | string[], fn: (gulp.WatchCallback | string)): NodeJS.EventEmitter {
-    return this._gulp.watch(glob, fn);
-  }
 }