add static page about
apply variable titles, about help home
Finish static pages
Merge branch 'static-pages' of https://github.com/kangkyu/sample_app into static-pages

Conflicts:
	app/views/layouts/application.html.erb
	app/views/static_pages/about.html.erb
	app/views/static_pages/help.html.erb
	app/views/static_pages/home.html.erb
	config/routes.rb
	test/controllers/static_pages_controller_test.rb