Warn instead of bailing out when autodie is too old

It turns out that even today LOTS AND LOTS of people and
smoke testers have old autodies (which actually makes sense)
so bailing out is actually not the right thing to do. It
causes tons of red in cpantesters, and is just super
unhelpful. Humans should be warned to upgrade, and this
does so.

Fixes gh-26 and gh-22
Only decoding @ARGV when called from main [GH-18]
Added testcase to verify @ARGV not decoded

Added testcase to verify @ARGV not decoded when not run from main.
Rewrote conditional statement on @ARGV decoding

As per suggestion of [Leont], “unless” is now rewritten as “if”
Only decode @ARGV in the main package

Merge branch 'HayoBaan-@ARGV' into dev

Fixes gh-18. Closes gh-25. Thanks to HayoBaan.