create capybara cheatsheet using rspec expect syntax for our student

[AmberWilkie]

I printed one for them from here: https://gist.github.com/tomas-stefano/6652111

[sigu]

I think we should just use the one linked above by @AmberWilkie

[diraulo]

Here's also a good resource to point students to http://cheatrags.com/capybara