Enables RSpec/ExampleWording and fixes all issues

Both avoiding 'should' and repiting 'it' on the tests description
improves reading them and also makes all descriptions consistent.

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

spec/helpers/verification_helper_spec.rb

@@ -3,18 +3,18 @@ require 'rails_helper'
 describe VerificationHelper do
 
   describe "#mask_phone" do
-    it "should mask a phone" do
+    it "masks a phone" do
       expect(mask_phone("612345678")).to eq("******678")
     end
   end
 
   describe "#mask_email" do
-    it "should mask a long email address" do
+    it "masks a long email address" do
       expect(mask_email("isabel@example.com")).to eq("isa***@example.com")
       expect(mask_email("antonio.perez@example.com")).to eq("ant**********@example.com")
     end
 
-    it "should mask a short email address" do
+    it "masks a short email address" do
       expect(mask_email("an@example.com")).to eq("an@example.com")
       expect(mask_email("ana@example.com")).to eq("ana@example.com")
       expect(mask_email("aina@example.com")).to eq("ain*@example.com")