Added social share info #43

# Changeset
- added varda-ved.svg
- added twitter and facebook share helpers

# To test
> This can only be tested once it's accessible from the internet, thus in `master` __But if it is in beta__

1. merge it to master
2. use [Facebook Debug Tool](https://developers.facebook.com/tools/debug) to verify facebook tags
3. use [Twitter Card Validator](https://dev.twitter.com/docs/cards/validation/validator) to verify twitter cards