Fixed deployment for app harness version 0.5

Fixes #2137 

- Includes a zipassetmanifest.json with a list of all of the files being deployed
- Delete the old app before pushing
- Deploys into a www directory

@devoncarew 
Was going off of the [this comment](https://github.com/dart-lang/spark/issues/2137#issue-34421813).  Looks like it's not necessary, though.  Done