Casper tests

@AlexeyMK @matteodem @yefim 
We actually have some tests now!

I'll keep writing more, and feel free to add to them.

I'm cool with just having one big file with all the tests, but I'm open to other suggestions.

Also, take a look at run_tests.sh. After running it `Terminated: 15` gets printed to the screen. I can't figure out how to stop it. That's what all the various `> /dev/null` are trying to do.

@matteodem Can you write some tests for the custom menu items when you have the time? I don't know that part so well.
could use a comment for us non-casperians.  

also, would be nice to explicitly list the casper dependency and a note (maybe run_tests.md?) about how to install dependencies to run tests?