Social Share | Share battle result via Facebook

[chhavi]

Background

As per #49 we want to share the awesomeness of playbox with the world! To start with, we need to add social media integration for Facebook and Twitter

Requirements

• Show a Facebook share button along with the battle result message. See https://github.com/kalamuna/playbox/issues/125#issuecomment-173434031
• The Facebook post should follow the below pattern
  • {winner name} just won an epic battle against {loser name}. Play other battles! {home page URL} #playbox #kalamuna
• Use Facebook API to generate the button: https://developers.facebook.com/docs/plugins/share-button