Add facebook share button to share a car -> used for referral feature

[tramyardg]

Refer a car by sharing a link to Facebook friends.
How?

• generate a share button for each car in the list
• using facebook's plugin
• use this code below and manually configure the href part so that it points to a specific car

<div class="fb-share-button" data-href="http://autoexpress.co.nf/" 
data-layout="button_count" data-size="small" data-mobile-iframe="true">
<a target="_blank" 
href="https://www.facebook.com/sharer/sharer.php?u=http%3A%2F%2Fautoexpress.co.nf%2F&amp;src=sdkpreparse" 
class="fb-xfbml-parse-ignore">Share</a>
</div>

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Reference main issue #15