v1.1.0

This commit adds support for asynchronous transformations.

## Community Contributions

 * #2 by @zbigg. Adds asynchronous support.

## Feautres

 * Asyncronous support by returning a promise

## Maintenance

 * Adds es6-promise dependency for compatibility with Node 0.10 to 0.12
 * Update outdated dependencies
 * Update README.md with async documentation

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gulp-transform",
-  "version": "1.0.8",
+  "version": "1.1.0",
   "description": "Perform arbitrary transformations on files",
   "main": "lib/index.js",
   "scripts": {