Moderate legislation proposals (#3602)

Moderate legislation proposals

- added a controller for moderation/legislation
- updated view to appropriate link + added route
- added a spec
- Feature test
- test for faded
- javascripts for visual effects

app/assets/javascripts/application.js

@@ -35,6 +35,7 @@
 //= require moderator_proposals
 //= require moderator_budget_investments
 //= require moderator_proposal_notifications
+//= require moderator_legislation_proposals
 //= require prevent_double_submission
 //= require gettext
 //= require annotator