Added rspec tests for layout_helper.rb

File is spec/helpers/layout_helper_spec.rb
https://www.pivotaltracker.com/story/show/82977718

This block appears to be testing 5 different things, keeping them separate is good practice (see http://betterspecs.org/#single). Don’t try to DRY out tests too much, tests should serve to document the behaviour of the object, if the behaviour is hidden behind complex logic, it will lose much of its value.