Revert "Version number is displayed on app index page"

Potential security issue.
Revert for https://github.com/aodn/go-go-duck/pull/23

To help @danfruehauf be able to enjoy his felafel properly.

Mr @danfruehauf, regarding comments on https://github.com/aodn/go-go-duck/pull/23 - I'll say again that it's not because I don't believe what you're saying, I would just like to do some more reading on this and thought you might have some specific links.  Even though you might be ultimately responsible for security, surely it is also in your best interests for the development team to be educated about these things (at least to some level) also?