Fix #709

Move functionality to FileCacheDriver, strip down manager class

We now use qa-global.js for all the in-page JS (except for qa-admin.js
which regular visitors don’t need).

For logged-out users only.

This fix checks for the question url . If it does not match with the
current URL then redirect to the correct one

Moved into question page so that it’s not on other pages, and so we can
obtain correct answer count.

Set to Unix line endings in repo; the gitattributes file means they
will be converted to suit the user’s system.