Unify results rendering

The results rendering functions (`renderBidsResults()` and `renderNIXResults()`) still duplicate a lot of code that could be moved to the `Results()` function. We could shrink these two functions so that :
- Make the main `Results()` function parse the layout template.
- The `Results()` function could also parse the template for each validator and then we can make the `renderBidsResults()` and `renderNIXResults()` functions simply return an `interface{}` which contains the data required to execute the template.

We could go one step further and have a single template for all validation results. Each function would then have to return a byte slice of their results as text instead of having them structured. The template would then simply add the text to the body of the common template.