CRM-13115 fix

in here : 

the  <code> if ($v == "amount") { </code> condition was coded in <code> function assignToTemplate() </code>to display 'contribution section' in email receipts for 'zero amount contribution' (so that line item entries can be displayed) relates to issue CRM-12771

Done a little modification to achieve the above pupose : 
now the code converts only zero amount value into money format.