Popular messaging app WhatsApp has now crossed 500 million users. The company which was bought by Facebook in February this year  - for a gigantic amount of $19 billion – has been steadily adding to its growing list of users. Last year in August, WhatsApp had 200 million users while the number doubled to 430 million in January 2014. The instant messaging app had also revealed that it processes 50 billion messages on an average every day. Jan Koum, co-founder of WhatsApp says in a post on...