Added funcinality for custom sender name and req_feat

req_feat is poorly documented parameter search for it inside this document to understand the functionality.
In general you need to specify it to make sure  that sender ID is set.
http://www.clickatell.com/downloads/Clickatell_Sender_ID_User_Guide.pdf

Example:
cktHttp.sendMessage('send to number', 'Message to send', 'Your custom ID', 48)