Add filters on budget investments index page

Now it's easier to change the investments filter. Previously we had to
go back to the budget index page, change the filter there, and then
select one heading.

Now the links to change the current filter in the budget index page
aren't needed anymore.

app/assets/javascripts/application.js

@@ -70,6 +70,7 @@
 //= require advanced_search
 //= require registration_form
 //= require suggest
+//= require filter_selector
 //= require forms
 //= require valuation_budget_investment_form
 //= require embed_video
@@ -133,6 +134,7 @@ var initialize_modules = function() {
   App.RegistrationForm.initialize();
   App.Suggest.initialize();
   App.Forms.initialize();
+  App.FilterSelector.initialize();
   App.ValuationBudgetInvestmentForm.initialize();
   App.EmbedVideo.initialize();
   App.FixedBar.initialize();