Formatting 'improvements' for SocialNetworking.tpl

Please refer to the attached patch.

The first change removes the <h2> tag and replaces it with a 'larger' 'bold' paragraph. I found that the <h2> was picking up formatting from my Drupal theme, and didn't appear to get any formatting from the CiviCRM CSS.

The second change adds some content after the Social Media buttons in the case where there is no 'Page URL'. This is the case for Petitions, for example. Without this extra content, the Social Media buttons appear 'outside' the box entitled 'Spread the word' (perhaps we are spreading the buttons

Ken