Bastion: allow adding additional menu items to detail sub-menus.

This PR allows arbitrary menu items to be placed in the sub-menus
on nutupane detail pages.
Merge pull request #3297 from waldenraines/pluggability

Bastion: allow adding additional menu items to detail sub-menus.
Bastion: Fixes broken coverage report generation.
Merge pull request #3320 from ehelms/fix-devel-coverage

Bastion: Fixes broken coverage report generation.
Bastion: Adding documentation on how to run HTML linting.
Merge pull request #3324 from daviddavis/html-lint-doc

Bastion: Adding documentation on how to run HTML linting.