Fixed 404 headers. REF: #1620
Fixed display of option choices when editing an option that does not use choices.
Removed redundant code from admin footer controller
Merge branch 'v1.5.6.x' of https://github.com/opencart/opencart into v1.5.6.x
Merge remote-tracking branch 'upstream/v1.5.6.x' into v1.5.6.x
added a practical method to class Request

With the method, now we can write
    if ($this->request->method() == 'POST')

instead of
    if ($this->request->server['REQUEST_METHOD'] == 'POST')

This makes the code a litte shorter.