Bugfix for (multiple) cookie extraction within a Request.

As part of improving cookie handling within Dancer2::Test, I (@veryrusty)
misread the HTTP::Headers docs and assumed it was doing the split when called
in array context. Oops, sorry!

Add tests and the split erroneously removed.
reflect changes
Merge branch 'pr/fix_cookie_extraction'
another small change
version bump
Merge branch 'release/1.140001'