Internet Explorer (IE) caching

[peterhambly]

Resolution of issue #75 highlighted an issue Internet Explorer (IE) caching. This cannot be detected from the REST result data. The only sensible way to resolve this would be to get the isLoggedIn REST call to return a date time string as well. This would probably prevent IE caching and could be checked to detect the caching and warm the user.

This will impact any REST call that returns the same data multiple times and so appears to not change but actually does (e.g. login status, rif40_num_denom data)