lml/ost#346: Make feedback penalty configurable.

- Add feedback penalty field to the settings store.
- Add feedback penalty to show and edit views.
- Add JS to show / hide penalty based on feedback required.
- Add help file for @kjdav with some help text.
- Ensure score detail page does not need any updates.
lml/ost#346: Fix cosmetic issues.

- Stop getting confused between JS and CS.
- Fix copyrights on changed files.
lml/ost#346: Fix JP's review comments.

- Use `unless` instead of `if not`
- Use floating point division.
Merge pull request #350 from lakshmivyas/feature/feedback-penalty

lml/ost#346: Make feedback penalty configurable.