sdk: Don't use _(...)

The CLI doesn't setup the _ function for i18n anywhere, so using it
causes exceptions.

Change-Id: I4309167af5a6ed4ffca67ede9f233ddd19166f78
Bug-Url: https://bugzilla.redhat.com/1135544
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>