Bug 20581: Add display of status_alias to staff vw

Bug 20581: Add display of status_alias to staff vw

- This patch adds display of the new status_alias value, when set, in
favour of the request's status value.
- It also allows the user to set a status_alias for an existing request.
When set, this value will be displayed in preference to the status.

Signed-off-by: Niamh.Walker-Headon@it-tallaght.ie
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>