Enable RSpec/RepeatedDescription cop & fix all issues

Read about cop at http://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/RepeatedDescription

spec/lib/migrate_spending_proposals_to_investments_spec.rb

@@ -31,7 +31,7 @@ describe MigrateSpendingProposalsToInvestments do
       expect(inv.heading.group.name).to eq("Toda la ciudad")
     end
 
-    it "Imports a city spending proposal" do
+    it "Imports a district spending proposal" do
       sp = create(:spending_proposal, geozone: create(:geozone, name: "Bel Air"))
 
       inv = importer.import(sp)