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/text_helper_spec.rb

@@ -3,12 +3,12 @@ require 'rails_helper'
 describe TextHelper do
 
   describe "#first_paragraph" do
-    it "should return the first paragraph of a text" do
+    it "returns the first paragraph of a text" do
       text = "\n\nThis is the first paragraph\n\nThis is the second paragraph\n"
       expect(first_paragraph(text)).to eq("This is the first paragraph")
     end
 
-    it "should return blank if the text is blank" do
+    it "returns blank if the text is blank" do
       expect(first_paragraph("")).to eq("")
       expect(first_paragraph(nil)).to eq("")
     end