Fix unicode dection on a number of Linux distributions.
Credit: @Darkhogg
Credit: @gagern
Reviewed-By: @iarna
PR-URL: https://github.com/iarna/has-unicode/pull/3
PR-URL: https://github.com/iarna/has-unicode/pull/4
Change the default on windows to be false, as international windows installs
often install to non-unicode codepages and there's no way to detect this short of
a system call or a call to a command line program.
Credit: @iarna
