#471 Additional Body Metadata for Draw Webhooks

[tariqksoliman]

Closes #471

All DrawFile* webhook actions now support the following valid injectable variables for URL and Body fields:

{created_on},
{efolders}, 
{file_description}, 
{file_id}, 
{file_name}, 
{file_owner},
{file_owner_group}, 
{folders}, 
{geojson}, 
{hidden}, 
{intent},
{is_master},
{public}, 
{public_editors},
{publicity_type}, 
{raw_file_description},
{tags}, 
{template}, 
{updated_on}