Add Net Promoter Score features

[darrendignam]

The OPF NPS tool can be used to generate feedback from users who download our tools. This service can be easily incorporated via the use of URL construction.

There are two URL varieties. One that can be link to or embedded in a web-view in the installer. Or the other that allows the score to be incorporated into the URL so that a 1 - 10 score GUI can be constructed in the app, and a user click will redirect them to the NPS score page with the score pre-populated.

In the fist instance the URL is constructed as such:
https://nps.openpreservation.org/dl/[STRING]

And to include a score:
https://nps.openpreservation.org/dl/score/[SCORE]/[STRING]

So one approach would be to have a URL like:
https://nps.openpreservation.org/dl/jhove-v1.22

Or a selection or URLs like this:

https://nps.openpreservation.org/dl/score/1/jhove-v1.22
https://nps.openpreservation.org/dl/score/2/jhove-v1.22
https://nps.openpreservation.org/dl/score/.../...
https://nps.openpreservation.org/dl/score/9/jhove-v1.22
https://nps.openpreservation.org/dl/score/10/jhove-v1.22