We want to be able to know whether the same file appears many times
in the layers of the docker image, because a file that appears many
times may represent a real inefficiency in the dockerfile.
* Fix two small compiler errors
Apparently, in go, `fmt.Prntln("\n")` is a build error - you can't
have a redundant newline there. Also, we had the wrong format string
somewhere.
* Use $GOPATH to find dep
When I first pulled this branch, all the tests failed because,
although `dep` was being installed to my local machine, it wasn't
being added to $PATH. Rather than mess with $PATH, I decided to
add $GOPATH/bin to the beginning of the invocation.
