onebox play store engine free item fix

+ instead of displaying 0 as the last item in the onebox
  for goole play items, shows a string "Free"
  read about it here:
  https://meta.discourse.org/t/play-store-onebox-issue/23146
google play template change

+ title is added to the template with a h3
+ development name is changed to h4
google play app one box

+ description text is limited to a max chars limit
Merge pull request #259 from digitalsurgeon/google_play_free_item_fix

onebox play store engine free item fix