Ensure `session_expire_delay` field exists before accessing it

Closes #1798

config/initializers/session_store.rb

 # Be sure to restart your server when you modify this file.
 
-if ActiveRecord::Base.connection.active?  && ActiveRecord::Base.connection.table_exists?('application_settings')
-  Settings.gitlab['session_expire_delay'] = ApplicationSetting.current.session_expire_delay
-end
+require 'gitlab/current_settings'
+include Gitlab::CurrentSettings
+Settings.gitlab['session_expire_delay'] = current_application_settings.session_expire_delay
 
 Gitlab::Application.config.session_store(
   :redis_store, # Using the cookie_store would enable session replay attacks.

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20150604202921) do
+ActiveRecord::Schema.define(version: 20150609141121) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -496,12 +496,12 @@ ActiveRecord::Schema.define(version: 20150604202921) do
     t.string   "bitbucket_access_token"
     t.string   "bitbucket_access_token_secret"
     t.string   "location"
-    t.string   "public_email",                  default: "",    null: false
     t.string   "encrypted_otp_secret"
     t.string   "encrypted_otp_secret_iv"
     t.string   "encrypted_otp_secret_salt"
     t.boolean  "otp_required_for_login"
     t.text     "otp_backup_codes"
+    t.string   "public_email",                  default: "",    null: false
   end
 
   add_index "users", ["admin"], name: "index_users_on_admin", using: :btree