motd: Allow for reading the current motd when no additional args given.

motd: Allow for reading the current motd when no additional args given.

Closes #155, merges #157

Squashed commit of the following:

commit bcb0810637c99223753629a2e55169b07ee9fe51
Author: Andrey Petrov <andrey.petrov@shazow.net>
Date:   Wed Aug 3 17:58:37 2016 -0400

    motd: Refactor inner conditions

commit ac28c8cb4e8dc2a0d23abe3dcf52b69175cde51b
Author: Aaron <aaron.ounn@gmail.com>
Date:   Tue Aug 2 09:38:36 2016 +0300

    Fix small issues with the help message

commit a80ae77e1d691a4ec7125be5441d4f6eea767a75
Author: Aaron <aaron.ounn@gmail.com>
Date:   Tue Aug 2 09:30:21 2016 +0300

    Print the motd if no parameters are passed

commit 2db1b3c123661cdbd622d5ba2ff81ede8cb8a951
Author: Aaron <aaron.ounn@gmail.com>
Date:   Tue Aug 2 09:29:41 2016 +0300

    Update the motd command's description