Fix build for android below 21
Fix build for android below 21

In res directory there's values directory that is required for all android versions and directory called values-v21, which is required only for Android version 21. In case you do not have installed latest Android version, this directory should not be added to your project.
Add copyResValues method, which copies res/values directory and res/values-v<version_number> directory to your project. This way when we add directories for other android versions, they will not break builds for older ones.

Fixes https://github.com/NativeScript/nativescript-cli/issues/299

jbristowe/nativescript-cli,e2l3n/nativescript-cli,NativeScript/nativescript-cli,tsvetie/nativescript-cli,NathanaelA/nativescript-cli,lokilandon/nativescript-cli,tsvetie/nativescript-cli,e2l3n/nativescript-cli,NathanaelA/nativescript-cli,NathanaelA/nativescript-cli,e2l3n/nativescript-cli,NativeScript/nativescript-cli,NativeScript/nativescript-cli,jbristowe/nativescript-cli,tsvetie/nativescript-cli,NativeScript/nativescript-cli,tsvetie/nativescript-cli,lokilandon/nativescript-cli,jbristowe/nativescript-cli,NathanaelA/nativescript-cli,lokilandon/nativescript-cli,tsvetie/nativescript-cli