Add expiration to session and repositories cache keys

app/controllers/sessions_controller.rb

@@ -20,7 +20,7 @@ def show
     require 'rva_calculate_results_service'
 
     @count = 0
-    @rva_results = Rails.cache.fetch("Session:#{@session.id}") do
+    @rva_results = Rails.cache.fetch("Session:#{@session.id}", :expires_in => 1.month) do
       RvaCalculateResultsService.new(@session).call
     end
 

app/helpers/repositories_helper.rb

@@ -2,7 +2,7 @@ module RepositoriesHelper
   # NOTE: The staff team will likely not lie about their github accounts... but it'd be nice to
   # add a separate field for them to have internal VCS accounts.
   def user_by_github(github)
-    Rails.cache.fetch("User##{github}") do
+    Rails.cache.fetch("User##{github}", :expires_in => 1.month) do
       User.find { |u| (u.profile.github.eql?(github) && user_is_staff?(u)) }
     end
   end