Do not use translations for the serial console messages

The serial protocol has to stay machine readable, without having
to cope with a ton of different human language variants. So
just leave it at the original english version.

Should fix ErikZalm/Marlin#1052
Merge pull request #1053 from foosel/fix/translated_serial_protocol

thanks...
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1