feat(auth): implemented users and user auth

#5 [Story] Create User Sessions

knockoutwhistweb/app/logic/user/SessionManager.scala

@@ -0,0 +1,11 @@
+package logic.user
+
+import model.users.User
+
+trait SessionManager {
+  
+  def createSession(user: User): String
+  def getUserBySession(sessionId: String): Option[User]
+  def invalidateSession(sessionId: String): Unit
+
+}