translator: additional help for google translate auto-detect failure
When translate command is used without source language, "auto" as source
language is assumed. It means that google translator is used and we let
google figure out what the source language is.
Problem is that the google translator will fail if the system that the
bot is running on does not have the json gem installed. This commit
addresses that problem by showing more informative error message instead
of a weird "none of the translators supports auto to en translation".
projects / rbot / commit
