Fixes to minor issues

I had a couple of issues when setting up my development environment.

First of all I got an error when running 'vagrant up' for the first time. The error was about the /vagrant/code directory not existing so I added the :create => true flag to config.vm.share_folder to fix this.

Secondly the build instructions didn't seem to match the current state of the repository. The ./go command didn't recognise the argument 'package' but seemed to work when I used 'build'. The directory for finding the *.omod file was also different to that in the instructions.