Barack Obama has paid tribute to his "beloved" grandmother who has passed away at the age of 99.Sarah Ogwel Onyanho, or known to many as "Mama Sarah" and to Barack as "Dani," was born and lived in Kenya.She "raised eight children, tended to her goats and chickens, grew an assortment of crops, and took what the family didn’t use to sell at the local open-air market."Sarah was the third wife of the former US leader's paternal grandfather, Hussein Onyango Obama, and Sarah raised Barack's father