Design navigation

This PR contains multiple changes:

+ It removes the <h2> on most pages and instead creates "@title" global that helps us display the full path of navigation on every page.
+ Phases out listOptions.html which is a very non-descriptive name, and changes it to "show"
+ Phases out the "handin" page and moves the handing form to the main assessment page. In the future, the handin form will also be available on other pages through a small button on the sub-navigation bar.