VMM/cli: Activated help subcommand.
Implemented Command.help_(), which reads the command's help message from
cli.clihelp.
========================
Managing relocated users
========================
relocatedadd
------------
Syntax:
| **vmm relocatedadd** *address newaddress*
| **vmm ra** *address newaddress*
A new relocated user can be created with this subcommand.
*address* is the user's ex-email address, for example b.user\@example.com,
and *newaddress* points to the new email address where the user can be
reached.
Example:
.. code-block:: console
root@host:~# vmm relocatedadd b.user@example.com b-user@company.tld
relocateddelete
---------------
Syntax:
| **vmm relocateddelete** *address*
| **vmm rd** *address*
Use this subcommand in order to delete the relocated user with the given
*address*.
Example:
.. code-block:: console
root@host:~# vmm relocateddelete b.user@example.com
relocatedinfo
-------------
Syntax:
| **vmm relocatedinfo** *address*
| **vmm ri** *address*
This subcommand shows the new address of the relocated user with the given
*address*.
Example:
.. code-block:: console
root@host:~# vmm relocatedinfo b.user@example.com
Relocated information
---------------------
User 'b.user@example.com' has moved to 'b-user@company.tld'