OAuth2 security:

OAuth2.java -handles sessions properly as well as signing of googles
certificates.

build.sbt -added google api client and google-http-client-jackson2
(necessery for signing)

User.java -added profile page with use of sessions, and a logout page

profile.scala.html -Represents the user profile page

routes -added:
GET         /users/profile          controllers.Users.profile()
GET         /users/logout           controllers.Users.logout()