use an arg validator in new mon to prevent passing an IP

Signed-off-by: Alfredo Deza <alfredo@deza.pe>

use the new hostname validator

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
add tests for the new regex validator

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
create a Hostname validator

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
tests for the new hostname validator

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
patch socket on tests that call cli directly
improve wording of IP error

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
update tests for the new wording

Signed-off-by: Alfredo Deza <alfredo@deza.pe>