Make P4Ruby aware that a charset of "none" means no charset at all.
Previously, using a P4Ruby >= 2014.2 against a server at least as new
could result in getting 'Unicode clients require a unicode-enabled server'
errors in appropriately. This was because we were treating 'none' as
a character set and enabling unicode mode on the client with that as
the charset to use for file content.
With the advent of .p4enviro files, this problem has been cropping up
frequently as that is the default value supplied when talking to a non-unicode
With this change, we now detect 'none' and use it to disable translation
as the user, and .p4enviro file no doubt intended.