Fix resource not found exception when using different package name in flavors.

- Send the package name from the default config to the testrunner to find resources
- TestRunner creates a custom AndroidManifest class that knows where is the correct R class thanks to the package name.
- Added different package names in the example for the flavors and for the buildtypes to demonstrate the fix.
- Specified a package name for free and paid flavors in example
- Specified a prefix for debug build type. After this we should have 4 different package names.
- The R class is still generated under the main package name in the main manifest.
- In order for the plug in to know the package name under which is the R class we add the package name in the defaultConfig. Otherwise the plugin won't find it and will use the robolectric default.