re-introduce url rewritting

We have temporarily dropped some support while working on the routing refactor that needs to come back into the codebase.

We can make use of a npm module that will handle the find/replace for us
https://www.npmjs.com/package/stream-replace

https://github.com/jembi/openhim-core-js/blob/5.3.0-alpha.1/src/koaMiddleware.js#L70-L72

Because we are working with streams now, we might need to make some updates to how the rewrite middle function to cater for the functionality