This is how she do: Rita Ora has been cast in the upcoming adaptation of "50 Shades of Grey." The 23-year-old singer has booked the role of Mia, the adopted sister of Christian Grey, this according to The Hollywood Reporter. Ora joins a cast which already includes Jamie Dornan (who will be playing Grey), Dakota Johnson (Grey's love interest, Anastasia Steele), and Eloise Mumford, Luke Grimes, and Max Martini. Ora is saying "R.I.P." to the singer she used to be and turning her focus to the major...