Fix a few typos and update README

Signed-off-by: Arnav Gupta <championswimmer@aokp.co>
update configs to build with latest gradle

  in line with Android Studio 0.4.0 which uses gradle 0.7.+ and
  gradle wrapper 1.9

Signed-off-by: Arnav Gupta <championswimmer@aokp.co>