Cherry picking ideas for 2.x -> 3.x

For my own reference, see here: https://github.com/loadsys/CakePHP-Skeleton/issues/16#issuecomment-52514629

Everyone else is welcome to add additional suggestions for useful things to migrate from the old 2.x skeleton into the new 3.0 skeleton. I'd personally place a priority on ease-of-conversion and overall value.

Start by reviewing the linked CakePHP-Skeleton issue comment and comparing the existing 2.x and 3.0 skeletons. Done would require selecting and prioritizing specific migration suggestions, but this issue does not identify a particular change, file, or test.

Written by the indexing model from the issue text.