add newPackage(String basename) function

For example to use case for `AndroidManifest.xml`,

- Dynamic build to package name with `writeResource()`
- For `authorities` property in `<provider>` attribute
    - to be install to multiple buildTypes application in gadget. *[fix for it](http://stackoverflow.com/questions/16777534/using-build-types-in-gradle-to-run-same-app-that-uses-contentprovider-on-one-dev)*

What do you think? :)