Remove the social icons if no go-local-bsocial

Addresses https://github.com/GigaOM/gigaom/issues/4654

Only try to show the social icons of `go-local-bsocial` is present.

Since this is public and should be submitted for the plugins directory, we might want to come up with a fallback at some point.
Get these via a filter, perhaps:

```php
$quote_permalink = get_permalink( $post->ID ) . '#quote-' . $this->quote_id;
$links = '<a href="' . esc_url( $quote_permalink ) . '" class="goicon icon-link-circled"></a>';
$links = apply_filters( 'go-quotes-links', $links, $quote_permalink, $post->ID, $this->quote_id );