Update problem.txt

I made it a little harder to miss the need for a 'for loop'.
Update problem.txt

I made it harder to miss the need for a for-loop.
fixed line lengths
Update problem.txt re: arguments

Making it clear that you do not need to add in arguments when running your program in the test environment.
Update problem.txt re: verify

I added a bit more information about 'learnyounode verify'.
Merge pull request #18 from thehack/master

I added more baby steps to problem.txt