core: Add login action group to NetworkUser role

For the sake of consistency with the other predefined roles, the
NetworkUser is being extended with Login action group (code 1300).

Therefore with this patch users with NetworkUser role only will be
capable to login into the User Portal.

Change-Id: Ib31ebaeabbe4f3b8bebae09dd451f9ef8b507e47
Bug-Url: https://bugzilla.redhat.com/894698
Signed-off-by: Moti Asayag <masayag@redhat.com>