[Feature request] Add option for specifing user folder, when adding a user.

[feikedonia]

Settings -> System & Accounts -> Users

See #832 and #834, currently when adding a new user, the specified user name gets set to the new /home/$USER, which isn't so crazy.
But maybe someone wants to add a user which allready has an /home/$USER folder. Also when removing a user you don't get the option to remove the /home/$USER folder, which, again, isn't so crazy.

But you don't have a way to graphically:

• useradd --create-home /home/jantjebeton oomGerrit or
• useradd --uid 1004 oomGerrit or
• userdel --remove oomGerrit.