What's the point of the change introduced in application.js:L751-L753, when it does not fix the method anyway?

IMO `installMiddleware` should throw an error to let the user immediately know that it does not work with express 4.x. That should be enough to make LB compatible with express 4.x, becase `installMiddleware` is sort of a dead-end, it's not described in the official Confluence docs and not used by `slc lb project`.