Test after hook order in the Test::Mapper spec

Validate that Cucumber::Core::Test::Mapper returns adds after hooks in
reverse order. See #64.
Use #unshift instead of #<< to add new after hooks

Fix #64 by using `Array#unshift` which prepends vs. `Array#<<` which
appends.
Validate the before hook order as well
Merge pull request #69 from erran/after-hook-order

Update order of After hooks