Change Set methods in Requests interface

Change Set methods in Requests interface

One UpdateRequest() public method is introduced instead of three Set
methods. Also Priority values are shifted by one. This will be required
to check if user has set Priority field (which takes zero value when it
wasn't set).

Change-Id: I2be2573edb93cb4a70f7f155786e6a18ba520270
Signed-off-by: Maciej Wereski <m.wereski@partner.samsung.com>
Reviewed-on: https://mcdsrvbld02.digital.local/review/49545
Reviewed-by: Aleksander Mistewicz <a.mistewicz@samsung.com>
Tested-by: Aleksander Mistewicz <a.mistewicz@samsung.com>