NS-CLI Readme

- Readme.md
- Contributing.md (Note that Contributing.md is borrowed from the AB CLI, so you might want to change it. This is just a placeholder for now).
This can be added in the bash profile as well. Check the Cordova docs for a reference :smile: http://cordova.apache.org/docs/en/3.5.0/guide_platforms_android_index.md.html#Android%20Platform%20Guide