Updates the release script to use the actual GOPATH directory as
previous problems with commit hashes / versions in `kompose version`.
Cleans this up in regards to all the `cd` and `cd ..` commands.
No need to `git clone`.
When developing Kompose, it's common to have the Docker Compose file in
the root directory.
Adding it to gitignore ignores it for any changes that could be
committed / pushed by accident.
