Solve "shared fragment" issue

[reidab]

Once upon a time, we implemented a system by which OCW would write out the result of rendering layouts/_header.html.erb to a static file, which would then by dynamically included in the osbridge WordPress and Mediawiki themes. As part of work to update things earlier this year, this functionality was removed due to its reliance on heavily-rewritten Rails internals.

This was only ever used by OSB, which is why I'm creating this issue here instead of in the OpenConferenceWare repo.

The importance of this feature is that it allows the other app's navigation to remain consistant, based on the current state of OCW. For example, when the schedule is announced, all of the apps that make up the site need to show a "Schedule" link.

For the CFP open date, we can work around this by writing these partial files manually. After that, we won't have any changes to the navigation until we announce talk selections. By that time, I'd like to have solved this issue.

One option is to reimplement the original functionality using modern Rails practices. Another possibility is to handle the menu rendering in JavaScript, by exposing a JSON endpoint that returns the appropriate menu structure. Additional ideas and hacking are welcome.

[reidab]

When manually writing shared fragments for osbridge, I realized that we either need to move the menu activation JavaScript back into the header or find another way to give that JS to the relying apps.