feat(task): acknowledge the user what urls have been changed

When using this task, I would like to see exactly what urls have been changed just like other grunt tasks. Especially work with grunt-usemin, the blocks are replaced so the scripts are not cdnified and this might confuse users. google-cdn needs to be modifed so also submitted a PR there https://github.com/passy/google-cdn/pull/22
Well I'm trying to follow the same pattern as grunt-usemin
https://github.com/yeoman/grunt-usemin/blob/master/lib/fileprocessor.js
A sample output:

Processing as HTML - dist/index.html
Update the HTML to reference our concat/min/revved script files
<script src="scripts/oldieshim.js" changed to <script src="scripts/oldieshim.a466b7b1.js"
<script src="scripts/vendor.js" changed to <script src="scripts/vendor.9d4fbcdc.js"
<script src="scripts/scripts.js" changed to <script src="scripts/scripts.2224122c.js"