Enable RSpec/DescribeClass rubocop rspec cop & fix issues

Manually fixes all issues & "stashed" false positives at .rubocop_todo.yml

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

spec/lib/graphql_spec.rb

@@ -35,7 +35,7 @@ def extract_fields(response, collection_name, field_chain)
   end.compact
 end
 
-describe 'ConsulSchema' do
+describe 'Consul Schema' do
   let(:user) { create(:user) }
   let(:proposal) { create(:proposal, author: user) }