Remove ApplicationController from SessonsController

Turns out that rails 5 had different autoloading behavior, and was
autoloading `Kracken::ApplicationController` when it referenced
"ApplicationController` in the `Kracken` module. I am not sure who had
the better behavior, rails 4 or rails 5, but this could be resolved by
dropping the dependency on the `ApplicationController` and just inheriting
from `ActionController::Base` directly.

Once I did that just needed to remove the `skip_before_filters` and
things seemed to work.

Author: csexton

app/controllers/kracken/application_controller.rb

@@ -1,10 +1,5 @@
 module Kracken
-  class SessionsController < ApplicationController
-    skip_before_filter :authenticate_user!, except: [:index]
-    skip_before_filter :handle_user_cache_cookie!, except: [:index]
-
-    def index
-    end
+  class SessionsController < ActionController::Base
 
     def create
       @user = user_class.find_or_create_from_auth_hash(auth_hash)